UNIVERSITY .QE. NEW ZEAIAND

THESIS ~ !. 2,2,- 1949-

STUDIES

POMATOCEROS COERULEUS, SCHMARDA_

With speoial referenoe to its Anatomy and

Histology, including investigations on the

Blood Ciroulation, Tube Formation, Feeding

and Experimental,EcolQSY; and a study of

the Ecol95X of the Association to whioh it

belongs at Taylor's Mistake, Banks

Peninsula.

COLL[;;":': ~ _·",k .; •.. "

tQ\.. ~11

r~ TABLE Ql CONTENTS • . ' '~\':~

SUMMARY. 1

1. INTRODUCTION. l

2. SYST.DdA.TICS. 4-

3. DISTRIBUTION. 7

4-. EX'l'ERNAL FEATURES. 8

5. THE PARAPODIA. 10

6. THE BRANCHIAL REGION.

(i) Anatomy. 11

(ii) Histology. 12

7. THE EPITHELIUM.

(i) The 'l'horaX'. 15

(ii) The Thoracic Membrane. 15

(iii) The Collar. 16

(iv) The Abdomen. 16

(v) The Cuticle. 16

(vi) Pigmentation. 16

8. THE STRUCTURE OF THE TUBE AND THE METHOD OF TUBE FORMATION.

(i) Struvture of the Tube. 18

(ii) Tube Formation. 21

9. THE MUSCUlATURE.

(i) Musculature of the Body Wall. 29

(ii) Branchial Musculature. 30

(iii) Muscles of Collar and Thoracio Membrane. ; '?~~118 31

..

12Pi~";'

(iv) Chaetal Muscles. 31

10. THE AI.TMENTARY SYSTD4.

( i) Anatomy. 32

(ii) Histology. 33

11. THE FEEDING MECHANISM.

(i) Methods. 35

(ii) Collecting Currents. 35

(iii) Re3ection Currents. 36

(iY) Nature or the Food. 36

(v) Transport ot Food along the Gut. 37

(vi ) Discussion. 37

12. GLAND AND MUCUS CELIS. 39

13. COELOMIC SPACES. 41

14. THE EXCRETORY SYSTl!M.

(i) Anatomy and Histology. 42

(ii) Excretion. 44

15. THE BLOOD SYSTEM.

(i) Previous Work. 45

(ii) Methods. 45

(iii) Anatomy. 46

(iT) Histology. 50

(v) Circulation. 51

(vi) The Blind-ending Capillaries. 52

(vii) Reversible stoppage. 53

(viii) Respiration. 54

16. THE NERVOUS SYSTEM.

(i) Anatomy and Histology. 56

(ii) Sense Organs. 58

17. THE REPRODUCTIVE SYSTEM. 59

18. DEVELOPMENT •

(i) Methods. 60

(ii) Egg and Cleavage Stages. 61

(iii) The Trochosphere. 62

(iv) Discussion. 64

19. PARASITES.AND COMMENSAIS. 65

20. EXPERIMENTAL ECOLOGY.

(i) Temperature Tolerance. 66

(ii) Salinity Tolerance. 67

(iii) Reaotion to other Adverse Conditions. 69

(iv) Influence of the Tube on Viability. 71

21. ECOLOGY.

(i) Introduotion. 72

(ii) Geography and Geology. 72

(iii) Climatic and Tidal Factors. 73

( i v) Methods 76

(v) The Relation of the Speoies to Tidal lavel. 78

(vi) Cri tioal Levels. 80

(vii) Connnunities. 82

(viii) General Zonation. 89

(D.) Disoussion.

22. GENERAL DISCUSSION.

APPENDIX I.

APPENDIX II.

107

112

113

APPENDIX III • LIST OF PLANTS AND ANIMAIB 114-FROM TAYLOR'S MISTAKE.

AOKNONLEOOEMENTS. 120

BIBLIOGRAPHY. 121

- 1 -CANTEREU: y UN\'.. TY (0,-,-' ~'!2

SUMMARY.

1. It is shown that the animal studied belongs to tm genus ~omatoceros. Its specific status is uncertain.

2. The species is widely distributed throughout New Zealand and has also been reported from South Afrioa.

J. The anatomy and some of the more interesting aspS) ts of histology are described in detail, comparison being made with other Serpulids.

4. The longitudinal muscles are~well developed and the circular musoles muoh re'duoed, an ada ion to the tubicolous habit.

5. One pair only of nephridia is present in the tholax, opening internally by large ciliated coelomostomes into the peristomial ooe1om and externally by a oommon pore at the anterior dorsal end of the body. Excretory products are probably extraoted from the blood in the form of guanine.

6. The nervous system consists of a brain, formed from two pairs of united ganglia, situated in the prostomium and united to two sub-oesophageal ganglia in the peristamial segment by dorsal and ventral connectives on each side. The two ventral nerve cords are widely separated and the giant nerve fibres are particularly well developed.

7. The blood system oonsists at a gut sinus, oonneoted to a ventral vessel by paired ring vessels in each segment. From the ring vessels branohes supplying the various organs of each segment arise. The oapillaries of these vessels end blindly. Movement of the blood is effeoted by rhythmio peristaltio contractions of the walls of the vessels. Details ot the oiroulation are desoribed. When the animal retracts within the tube the blood circulation stops. This reversible stoppage of the blood is brought about by the aooumu1ation of oarbonio aQid. The course of the respiratory currents within the tube ~ described.

8. The oiliary feeding mechanism of the crown is described, the food consisting of finely divided plankton and detritus.

9. The form of the tube is extr~ely variable. lt is shown to be composed of a glyco-protein of a mucoid nature

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in which crystals of calcium carbonate in the form of aragonite are deposited. lt is formed as a discontinuous secretion from gland cells of the collar region of the peri­stomial segment. The evidence so far collected points to the sea-water as the source of calcium.

10. The development from the egg to a fully formed trochosphere has been followed. The egg is small with little yolk and development is rapid.

11. A large percentage of the worms is infected by a gregarine parasite and large numbers of a commensal Ciliate, ~richodina sp. are present.

12. Experimentally Pamatoceros is found to tolerate a wide variation of temperature and salinity, and is shawn to tolerate exposure and coverage by sand to a large extent.

13. The habitat of Pamatoceros coeruleus is described in detail and a detailed analysis of the community at Taylor's Mistake, ~anks ~eninsula, to which it belongs)has been made. The relationship of a number of different speCies of plants and antmals to tidal level and exposure to air is discussed, comparison being made with other surveys. Oritical levels for the different species have been detected. Pomatoceros coeruleus is shawn to be a dominant organism in the Ch8.maeslphO-lIaUllus planulatus Association of the littoral rocky shore. ~he general zonation ot the plants and animals on the shore is discussed in relation to tidal level and exposure to wave action. A comparison is made with other surveys carried out in Australia, South Africa, North America and Great ~ritain. A fund~ental basic zonation of typical indioator animal species, oommon to the temperate regions of the world is recognized •. This basic soheme is, a L1ttorin~ zone. oocupying the highest level on the shore followed by a Barnaole zone below with a Laminaria or Kelp zone occupying the sub-littoral fringe. ----

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1. INTRODUCTI0lt.

The Polychaeta of New Zealand have not received much attention from investigators, and there has not yet been a comprehensive treatment of the group. This is especially true for the littoral specie, since a large proportion of the described species have been obta.ined from dredging operations carried out by various Expeditions that have visited the New Zealand shores. McIntosh (1885) in the Challenger Reports, Vol. XII, has described a number of species trom New Zealand/ and later Benham sent a collection of 93 species to Germany and these were described by Ehlers (1904, 1907). The Th. Mortensen Pacific Expedition collected Ilf/ species from the New Zealand seas and they have been described by Auenger (1928). Both Hutton and Benham have also added several species to those recorded from New Zealand. Nearly all the work done so far has been the description of species, mainlY from preserved material, and the only account of the anatomy of a New Zealand species is' that of EU!hione sguamosa (Lepidonotus giganteus) by Benham and ~hompson (1900). There are no accounts of the ecology of any of the New Zealand species.

This Thesis is a study of a cammon New Zealand Serpulid, Pomatoceros coeruleus Schmarda. It is widely distributed throughout New Zealand and in many places occupies a position in the marine littoral communities comparable to that of the bivalves and barnacles. The worm shows a wide range of adaptability to different types of environment, being found on hard surfaces from the open coast to the muddy upper reaches of L¥ttelton Harbour and tidal inlets such as the Heathcote Estuary. It thus presents many interesting ecolog­ical problems and an attempt has been made to solve some of them. As an experimental animal Pomatoceros coeruleus has several advantages, it is plentiful and very easily kept in the laboratory, specimens having been kept in a small aquarium for over twelve months. Its anatomy and histology have been worked out and throughout an attempt has been made to relate structure and function and fit the information eained ~gainst the background of the ecology of the organism.

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2. SYSTEMATICS.

In"his 'Index Faunae Novae Zea1andiae' Hutton lists fifteen speoies of Serpulids and mentions that no attempt has been made to. re-examine them. Auenger (1928) and Ehlers (1904, 1907) have reoorded several of the speoies in Hutton's list and desoribed several new speoies. From an 6xaminatim of the desoriptions given of the various speoies it appears that many of the speoies are synonymous. The speoies whioh forms the subjeot of the present investigation has been desoribed or reoorded at various times under different generio and speoifio names. The following is a table of synonyms.

1843

1861

1863

1865

1876

1878

1878

1878

1878

1885

1904

1907

1907

Ver.mitus oaraniferus Gray, Dieffenbaoh's New Zealand, II, p 242.

Plaoostesys eoeru1eus Sonmarda, Neiue Wirbel10se Thiere, (2), p 29, Pl. XXI, fig. 178.

Pamatooeros stri,ioeps, Moroh, Rev. Serpe p 66, Quart. 1.0., I t P 521.

Vermi1ia ~ Quartrefrages, Hist. Nat. Annel. ii., ~.

Vermitus oariniferus, Baird, P.L.S., XI. p 12.

Vermi1ia cari.iferus, Hutton, T.N.Z.I., xi, p 326.

Vermi1ia oaeru1ea, Hutton, T.N.Z.I., xi, p 326.

Vermilia greyi, Hutton, T.N.Z.I., xi, p 326.

Vermi1ia strigioeps, Hutton, T.N.Z.I., xi, p 326.

Pamatooeros strigioeps, MoIntosh, Challenger Reports, XII, p 520, pl. lU, Figs 3, 4.

Pomatooeros strifiOetS, Ehlers, Neusee1andisohe Annelid n, t P 67, pl. IX, Figt 11-19.

Pamatooeros ooeruleus, Ehlers, Neusee1andisohe Annelialn, II, p 29.

8pirobranohus? oariniferus, Ehlers, Neuseelandisohe ADne1idln, II, p 29.

1919

1927

1928

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Pomatoceros caeruleus, Fauvel, Annelides polychetes de Madagasoar, de Djibouti et du Golfe Persique Arch. Zool. Paris, 58, p 315., pIs. 15-17.

Pomatoceros ooeruleus, Benham, Brit. Antarftio ("Terra Nova") Expedition, Nat. Hist. Rep. Vol. VII.

Pomatoceros coeruleus, Auenger, Papers trom Dr. Th, lortensenf~ Paoific Exped. 1914-16, XXXIV,p 217.

The species studied agrees in every detail with the definition of the genus Pomatoceros as given by McIntosh (~24) and Fauvel (1927). The triangular peduncle, bearing two lateral wing-like projections (Fig.~, ), and the calcareous plate on the operculum bearing two short spines are diagnostic oharacters. The form of the chaetae also agrees.with the descriptions given. The status of the species, however, is not so certain.

In 1843, Grey, in Dieffenbach's Travels in New Zealand, described a Serpulid under the name of Vermitus cariniferus which woe, as far as can be ascertained tram the description, the species under investigation. Hutton (1878) lists this species and also Ver.milia caerulea, which was desoribed by Sohmarda (lSbl) :from "tIlb [ape or Good Hope as Plaoostegus ooeruleus. Hutton regarded the t?10 species as synonymous. Ehlers (1903) described some Serpulids from French Pass as Pomatoceros stri8iceps Morch (1864). In 1907, after the examination of further specimens from Auckland Harbour, he- came to the conclusion that the worms described in 1903 were synonymous with Pamatoceros coeruleus Schmarda and accordingly combined the two species. Auenger r 1928) desDtibed worms collected from Cape Maria van Dieman, Ponui Is., Slipper Is., and Kaipara as Pomatooeros ooeruleus. The description given by Auenger tits specimens collected on Banks Peninsula and I have compared them with some worms oollected at Ponui Is., one of the localities represented in Auenger's oollections. Comparisons have also been made with material from Auckland Harbour, Dunedin and Stewart Island. All the specimens examined so far belong to the same speoies.

The description of Pomatoceros stri6ice~s given by Ehlers (1903) does not apply to the specimens examined trom the above looalities. In his figures he shows that the edges of the collar folds are toothed and that the thoraX and

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abdomen grade into one another, the p~ecting membrane at the posterior end of the thorax uniting the two flaps of the thoracic membrane (Fig. 2. J~Which is present in all the specimens I have examined, being absent. The descriptllon given by Mclntllh (1885) for Pomatoceros strigioeps also does not fit the specimens I have exalnined.The worms desoribed by McIntosh were dredged in 150 fathoms off the coast of New Zealand opposite Cook's Strait. The species which forms the subject of the present investigation ends abrpptly above low tide mark and no specimens have been observed in, or obtained from the sub-littoral regions.

Following Auenger (1928) and Benham (1927) the species under investigation may be provisionally called Pomatoceros coeruleus. Unfortunately Schmarda's original description was not available for comparison. Benham (1927) in 'describing worms obtained from a rock pool at the Bay of Islands, stated: "It is curious that this speoies was not included in the South African polychaetes studied by Mclntos~ Had it not been for the precise statement by Ehlers that he had compared the worms sent from New Zealand with Schmarda's type I should have doubted whether the two are identical." If, as seems the case from the description, the worms described by Gray (1843) as Vermitus caranlferus are the same as the species under investigation, the specifio name caraniferus would take precedence over coeruleus for the New Zealand species.

~11g. 1. Map showing the distribution of Pomatoceros coeru1us.

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3. DISTRIBUTION.

The species Pomatoceros coeruleus appears to be confined to the sub-tropical and temperate regions of the Southern Hemisphere. It has been reported from Cape of Good Hope (Schmarda 1861), Madasascar (Fauvel 1919) and New Zealand (Ehlers 1907, Auenger 1928). There is no record of the species from the Subantartic Islands below New Zealand.

It is widespread throughout New Zealand having been reported from Auckland Harbour by Ehlers (1907), from Bay of Islands by Benham (1927) and from Cape Maria van Diaman, Ponui Is., Slipper Is., and K8ipara by Auenger (1928). I have oollections from Auckland Harbour, Ponui Is., Banks Peninsul~ Oamaru, Dunedin and Stewart Island. Oliver (1923) has recorded the species as Vermilia caranifera fram Tauranga, ~ of Islands, Auckland Harbour and Hauralli Gulf. The species then occurs as a member of the rocky shores associations of the littoral region throughout the three islands of New Zealand.

It has been found on all types of rock from hard volcanic rocks to soft sandstone. Its distribution in the littoral zone is relateo, to tidal level and exposure to wave action. The effect of these factors is described in the section on Ecology. Th~ species can also tolerate a fairly wide variation in envl:t.CQI8ltal factors ,such as sallni ty and the turbidity of the ' sea-waten being a common membe~ of tile hard surface associations of estuaries.

F A tar"or 0 right side . ra hia! crown

se D base

shown.

fi­of t

the e

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4. EXTERNAL FEATURE.S.

The size of the worm is very variable and depends largelr OR age and to a lesser degree OB the growth habit of the tube. The average length of an adult worm with mature gonads i. trom 2 to 5 c .m. The Dumber ot segme:ats is also variable, usuallY'tO_1OO When the tube is adhere.t to a solid substratum the dorsal surtace is always towards the substratum. The body ot the worm is divisible i.to three regioRs, the prostomium, the thora.x and the abdomeJl. The thoraoic segments are larger than the abdomilil.al .. the average width ot the tormer bei:ag. 9 o.m. end the latter·;) c.m. The general appearanoe of the worm call be seea ill Fig. 2.

The prostom1um is much reduced and carries the two ha1Tes ot the branchial crOWD, each consisting ot aumerous tilaments. The structure ot the branehia1 orown will be described i. detail later. The colour ot the crow. is iRvar­iably deep blue barred with white on the lower halt. OR the anterior dorsal surtace ot the prostamium there is a bli.d-endiag inpushing ot the bod7 wall, the dorsal pit (Figs. 27 & 34.). On . the dorsal root of the pit there is a ridge terminating in the opening of the single pair at nephridia. (The word dorsal in this paragraph and in the to11owing sect10ns reters to the dor.l surtace ot the worm and does not reter to the position at the worm in relation to the substratum.)

The thorax consists ot seven segments all of whioh bear chaetae. In the tirst or peristOJdal segment the ehaetae are reduced and the uncini are absent, being present on the remainder ot the segments. The thorax bears a membranous out­growth, the thoracic membrane, having the torm ot two longitud­inal tolds, one on each side dorsal to the parapodia. The membranes are united posteriorly by a transverse ventral told and anteriorly by another told at the anterior end of the peristamiel segmeDt, the collar told. The collar is divided into three parts, two lateral tolds and a ventral one, the latter triangular in shape, ending in a bluntly rounded point. When the animal is retracted into the tube the collar poin~s torwards; but is rolled back over the opening at the tube when expanded. The two thoracic membranes are closely applied to the inner surface of the tube and may overlap torming a supra­thoracic canal (Fig. 45. ) •

The abdomen consists at trom 60 to 90 aepents ot which the first 1s achaetous. It is rounded dorsallr and

,. . ...

" .. ..

Fig . J . o diff'ere t

e, \

ypee of 0 ercu •

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flattened ventrallJ. A ciliated ventral grooTe runs tram the anus to the posterior end of the thorax, where it divides in to two ciliated tracts which run round to the dorsal surface tit, the groove between the body wall and the posterior flap at the thoracic membranes. Towards the posterior end the segments beoome flattened and reduoed. The ter.minal segment or pygi4ium is acheetous and ends in two lobes - the anal papillae.

The oolour of the body is very" variable rall8ing trom pale yellow to a very deep blue. The abdomen is usuall1 ligbter in colour than the thorax. The green colour of the blood in the capillaries shows through the thoracic membrane and the collar folds. Worms obtained from the muddy waters at Governor's Ba.y, at the upper end of ~telton Harbour, are coloured a d.,p blue, a.lmost black on both the thorax and a bdamen. Those trom Taylor's Mistake, Banks Peninsula are usually bluish-brown on the thorax and flesh ,oloured on the abdanen.

FiS· !t. Notopodial bristle trom the peristomial segment.

FiS· 2· Notopodial bristle trom a thoracic segment.

FiS· 6. Tip ot a notopodial bristle.

Fis. 7. Bristle trom one ot the abdominal neuropodia.

FiS· 8. Uncinus trom a thoracic neuropodium.

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5 • THE PARAPODIA.

A pair of parapodia are present on all the segments of the body excej)t the first abdominal and the pygi4ium.. The thoracic parapodia consist of a dorsal notopodium and a ventral neuropodium. The notopodia are narrow lobes, elongated in an antero-posterior direction and investing the bases of the long chaetae which are arranged in two rows. The neuropodia have the form ot thick ,transverse ridges pro­jecting backwards and ending 40rsally in rounded flaps carer­ing the notopodia. On the posterior side of each neuropodium there is a raw of uncini.

In the abdomen~ as in all the Sabelliformia, the position ot the two types of chaetae are reversed, the long chaetae being ventral and the uncini dorsal. TUe neuropodium is much reduced and the notopodia are small swellings on the lateral sides of the body. .

There are about 40 long bristles in each thoracic segment except the first where they are fewer and much slenderer. The bristles taper to a fine point, the end being curved with a pair of wings. These wings are striated.

In the abdomen there are only 5-9 bristles per segment. The tip is expanded with a curved prooesses on one side. There are numerous tine teeth along the edge.

The uncini vary in number according to age and are fewer in the more posterior segments. The number varies tram about )0 to 60 in the abdomen and 80 to 150 in the thora~ Each uncinus consists of a broad basal plate with strong curved teeth pro3ecting trom it, the last one, being some­what moditied. The number of teeth varies trom 7 to 12.

t~\oYV"\e",t h(; .. ~~d {o\d~

Fis, 9. Diagramat.ic view of the branchial crOWD. as seen fram the ventral surface wjth the filaments spread out.

- lJ -6. !'lIB BRANCHIAL REGION.

( i ) ANATCRY •

The so called gills are now generally termed the branchial crown. Morphologicall1 the crown represents the palps (Pruvot l88S, Johansson 1927). It is a ciliary feeding organ

'as well as respiratory. . The branchial crown is composed of two lateral lobes united at the base on the dorsal side. They curve round on either side of the mouth in the form of a semi-circle. Each bears nmnerous filaments, usuall1 a bout '#"5 on each side; but the number varies oon'siderably with age and may differ for the two sides of the same branchial crawn. The most ventral filaments are shorter than the rest. The filaments are united for a bout half their length by a thin membrane, the basal membrane. (Fig. 9. ). kch filament on a tully grown worm is about /-5 c.m. in length and bears two rows of pinnules arranged in pairs. Distally each pinnule ends in a bluntly tapering point. Towards their bases the filaments give rise to a pair of parallel folds, the basal folds, which run along the filaments for the first fifth of their length.

The two halves of the branchial crown form a wide funnel, at the centre of whiCh is the mouth. The,. are united on the dorsal side of the bod,. by the dorsal ~nd ventral lips. The dorsal lip joins the outer basal folds of the two most dorsal gill filaments. At the points where they jOiB there arise two long tapC?ring structures, the so-called p~lps. ThEf/ are grooved on the .mer side and richl,. ciliate40u' "t.b.e ventral and outer surfaces. They are not hanologous with the palps "* the Errant Pol1chaetes. Sergrove (1941) in bisstudy of the development o~ Pamatoceroa trigueter found that thepalps were 4B~ived tram the fIrst, CD the most dorsal, of the branch'.l filaments. The ventral lip forms a pair of low felds running round the bases of the basal folds of the gill fil~ents. A groove is formed between these and the 'Qasal membrane. -,' , Th.is groove curves dorsall,. and continues into the aauth which lies between the dorsal lip and.the median part of tlie ventral lip. The mouth leads into a creaantric shaped buccal c~vity.

The operoulum arises tram the ventral base'ot'the l~­band lobe of the branchial crown. Zeleny (1965) by a studY.ot the development of Hydroides dianthus has s,hown that the operculum represents one at th8branchial fl~nts. Sergrove (1941) found that the operculum at Pamatoceros,trigueter is developed tram the third filament at the lett-hand lobe. If the operculum is removed it is always regenerated on the same side. There is no r.dimentery operculum on the right-hand side as in some Serpulids. The stalk or peduncle is ususlly

Fig . 10.

Fi. 11 .

\

ransverse section of a branohial til m nt . 00

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triangular in cross-section \Fig. 3J. ~t is composed of two segments with a groove between them and it is at this point that the operculum breaks if it sticks in the tube, when the wcrm is being removed. -·ihe.-d1stal segment bears at the antero-lateral corners two-processes which vary considerably in size. 'rhe operculum itself. which 1s uaual17 longer on the dorsal side than on the ventral is also extrael,. 'ftriable. On its cuter s~faoe it bears a calcareous plate which may have two come al projections. These may be absent and the calcareous plate may be tormed of several layers.

( ii ) BISTOUlGY.

Since- the individual worms ere small most of the anatomy has to be made out from microscopio sections. For general anatomical and histological work the worms were fixed whole in Bouin~"'t Susa, Zenker's and Rellt t s fixatives, embecil ed and cut whole. A variety of stains were used including Heidenhaints with various counter-stains, Delafield's, Mallory's, Masson's trichrome stain, Sarranin and Light Green, Mannts double stain, and Chlerazol Black. Special techniques ale described in the a~propriate sections.

The pinnules (Fig. 10) are more or less oval in cross-section, being flattened on the inner ciliated surface. The cells forming the epithelium of the pinnules are of three kinds: (a) ciliated oells, (b) non-ciliated epithelial cells and (c) mu~gland cells. Ciliated cells occur on the frontal faces and the latero-trontalc-orners of the pinnules. In transverse section 'those on the frontal face are usually three or four in number. The cells are elongated, with large oval nuclei and rather dense cytoplasm, having a striated appearance in stained sections. ,The free ends of the oells are covered with short cilia which arise from a row of basal granules just within the cell and pass through the thin cuticle. On either side of these cells there is a row ot large cells bearing the lata:-o­fronta 1 c"illa.The cYtoplasm of these cells is densely stain­ing with Delafield's and· the nucleus large with scattered reticular ohromatin and a large nucleolus. Each cell bears a group of long tine cilia. When the pinnule of a living VI) rm is viewed under a mioroscope they appear as a single stout cilium. In fixed material they have separated into separ_te cilia joined to a row of basal granules from which a group of tine fibrils run in towards the nucleus. Similar compound cilia have been reported in Sabella (Nicol. 1.930) and on the gills ot M~ilUS (Carter, 1924). Immediately outside these cells bear~ the latero-frontal cilia there is a raN of mucus cells. The rest of the pinnule is covered by an epithelium

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o~ rather squarish cells which stain lightly with HeideDhein's and possess a thick cuticle. These cells contain blue pigment granules which are most numerous towards the periphery of the cells.

Within the o-.tre of the pinnule there is a large oeelomic space which is a continuation of the coelomio cavity of the peristomial segment. The coelomic space contains the· blind-ending blood vessel o~ the pinnule. on the inner side o~ the coelomic cavity there is a row of longitudinal .... li ~ibres.

The epithelium of the branchial filaments is composed of the same types o~ oells as that ot the pinnules. The outer and lateral sides are covered by' columnar, non-ciliated cells with a well-defined basement membrane and a thick cuticle. On the inner face there 1s a ciliated groove lined with cells having the same appearance as those bearing the trontal cilia of the pinnules. Globular mucus cells which stain darkly with the speci~ic mucus stains, mucioarm1ne, muclhaaatin, tldollill and tolut,in blue are numerous within the ciliated grOOTe. In lIbe c4mtre there is a ooelomic space continuous with that ot the p1Jm.ules, containing a blood vessel. Between ... coelom and the epithelium, in each corner of the ~ilament, there is a band of longitudinal muscles, the internal and external branchial muscles. Underneath the basement membrane, between the two inner groups o~ muscles lles a nerve, the internal branchial nerve, while on each outer corner, between the bas es of the epithelial cells, there runs a smaller nerve the external branchial nerve. '

Tewards their bases the filaments, when seen in transverse section, are very elongated and the branchial muscles have fused to form a single inner and outer muscle. The basal ~olds are low and are ciliated on their inner surfaces. The besal membrane is composed of two layers of unoil1ated epithe .... with ~used basement msabrane ••

The dorsal and ventral lips are caaposed of two layers of epithelium separated by connective tissue oontaining spaces wlthin which run numerous blood vessels. The inner lay'er is caaposed o~ cilia.ted oells between which are numerous muous-gland cells. The structure of the cells is similar to that of the ~ilamentar groove. The outer layer consists of squarish cells covered with a cuticle. Some of the cells o~ the central parts of both dorsal and ventral lips are ciliated the cilia occuring in tufts. The outer sides of the dorsal lip are uni~ormly oiliated.

, \

coe\o

\ 0

Is . 12 . Transve~ cct':'(n (1 th

______ --c. I l,

at th t .

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The ~ (:rig. 12.) is deeply grooved on its outer surface which rs-covered by an unciliated epithelium with a thick outiole, similar to that "of the filaments and pinnules. This unol1iated epithelium extends onto the ventral side of the palp. The epithelium of t~e inner and dorsal surfaoes oonsists of ciliated oells and mucus-gland oells. The ciliated cells are columnar with denseoytoplasm. and bear long dense cilia. Large mucus-gland oells tapering to a point underneath the cuticle are scattered throughout the ciliated oells. The ventral portion of the palp contains a large ooelomic space in which runs a blood vessel. On the inaerside of this coelomic cavity there is a group ot longitudinal muscle tibres. The coelomic cavity extends into the dorsal portion which also contains blOOd-vessels and muscle tibres.

Ventrally the palps tuse with the outer margins ot the dorsal lip (Fig. 13.). The ventral half at the palp is continued baok as a non-ciliated ridge, while the dorsal portion runs back as a parallel told ot epithelium ciliated on its inner and dorsal surfaces _. Eventually the ridge and the ciliated told meet and tuse. The structure ot the palp shows a resemblence to that ot Pomatooeros trigueter. Thomas (1941) states that the absence ot cilia in the outer groove is note­worthy; but that no explanation oan be suggested. From the structure, the way it originates from the dorsal lip and the distribution of the cilia it would appear that the ventral halt represents the filament ciliated on its inner surtaoe and the dorsal portion represents a raw ot fused pinnules. The other row ot pinnules has disappeared~ As mentioned above , Sergrove (1941) has shown that in development the palp arises trom the tirst tilament.

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- 15 -

7. THE EPITHELIUM.

The epithelial cells vary great~ in appearance and size in the various ~egions of the body. The various regions of the body will be discussed in order. Observations were made on livin~animals aided by the use o~ intra-vitam stains and on sectio~terials stained by the methods mentioned above.

(i) THE THORAX.

The epithelium of the sides and ventral surface of the thorax (Fig. 14) consist of tall columnar rather irregular cells with a very thin cutivle. On the ventral surface mucus-gland cells are abundant, forming the ventral gland shields which are common in Serpulids and Sabellids. ~he epithelium forming the outer wall of the parapodium is also composed mainly of mucus-gland cells forming a parapodial gland. Immediately underneath the ventral thoracic epithelium is a band of connective tissue containing large irregular spaces in which run numerous blood vessels. On the dorsal surface there is a columnar epithelium of lightly staining cells resting on a well defined basement membrane. The nuclei lie towards the periphery of the cells which are covered by a thick cuticle. In the central area of the dorsal surface isolated cells are frequently ciliated, the oilia having a tufted appearanoe. On either side there is a well defined ciliated traot, all the cells being uniformly covered b¥ long ci11a passing through the thick cuticle. (Fig. l5.}. This pass~ge of cilia through the thick cuticle is a characteristic feature of the Sabelliformia and not commonly found outside the group.

( 1i ) THE THORACIC MEMBRA'NI.

The thoracic membrane consists of two layers ot epithelium with * not very well de tined basement membrane. Thera is no connective tissue between the two layers which are separated by a network ot irregular spaces within which run numerous blood vessels. The cells ot the inner layer resemble those of the dorsal surface ot the thoraX, except that the outer ends of the cells are darkly stained. All tIle cells are uniformly covered with tairly long cilia. The ~uter layer consists ot rather irregular darkly staining wells without a detinite cuticle. Frequently these cells are packed with blue pigment granu168.

Fig . 5.

c. Ie..

I

I

Photo ero raph of t ansverse seotion through t e dorsal ep theli of the prost 0

- 16 -

(iii) THE COLLAR.

The collar is composed of two layers ot cuticular­ized epithelium which are separated at the base of the collar by connective tissue and muscle fibres. In the free part of the collar there is no connective tissue. Numerous blood vessels run between the two layers. The gland cells ot the collar region will be discussed in the section on tube formation.

(i v) THE ABDOMEN •

The dorsal surface and sides of the abdomen are covered by an epithelium of short cells with a thin cuticle and a well defined basement m .. brene. In the mid-ventral line there is a groove lined with low cells bearing a dense covering of short cilia. On either side of this groove are large irregular cells forming the ventral gland shield areas. In the anterior region of the abdomen mucus cells are rel­atively scaree. They become more abundant towards the rear, where the majority of the cells of the ventral gland shield areas are mucus secreting cells. Mucus glands are also very numerous in the epithelium of the notopodia throughout the abdominal region.

(v) THE CUTICLE.

The thickness of the cuticle covering various regions of the epithelium, particularly on the anterior part of the body, is noteworthy, In certai~regions of the body this cuticle may reach a thickness of If;) JA. It otten shows a striated appearance and in one preparation stained with safranin the cuticle shows a darker staining outer layer and a similar layer about the middle of the cuticle. In general it shows the same staining properties as collagen fibres. blue with Mallory's and Mann's double, ~tain, green with Masson's, pink with haematoxylin and ffn.\tbrosin. The cuticle is not stained by the specific mucus s~ains, muci-carmine, muci-haematin, thionin and toluedin blue.

(vi) PIGMENTATION.

The blue colour of the gills and other regions of body is caused by blue pigment granules which are present in the epithelial cells. In sections these granules are seen

- 17 -

to be concentrated towards the outer ends of the cells. The pigment is very stable, surviving fixation in Susa, merc~ic chloride, Zenker's, Bouin, formalin and alcohol and undergoes paraffin embedding uncha~ed. It is not dissolved or destroyed by prolonged immersion in the following organic solvents, alcohol, benzene, toluene, ether, acetone, 8.nd chloroform. The granules are slightly soluble in water to give a pinkish solution. They dissolve in dilute acids and alkalls ". to give solutions of varying colour, pinkish-brown with acetic acid, light brown with ammonia, and brown with sulphuric acid, sodium hydroxide and potassium hydroxide. strong oxd4iz~ng agents' such as bromine water, hydrogen peroxide and nitric acid rapidly destroy the pigment8~ These

-reactions indicate the presence of either melanin or the so­called 'chromo-lipoids'. (Verne 1926). To determine the exact nature of the pigment further chemical and spectographic analysis is necessary. On death the blue colour of the branchial crown changes to brown. If worms are kept in water in which they reduce the oxygen' content to practically nil the same colour change occurs while the worms still remain alive. When transferred to fresh aerated sea-water the blue colour is gradually restored. This change presents an interesting physdological problem.

Fi g. 16. hotogra_ h of Porna "oe ros coeruleus grow­ing on rock at Taylor ' s MIs aka, "'B n s Peninsula.

Fig . 17 . Photograph of the ends of the tubes in Flg.16 showl g the pro eoting spine •

8.

- 18 -

THE STRUCTURE OF THE TUBE AND THE Ui'HOD OF TUBE FOI&ATI6N. - ---

(i) STRUCTURE OF THE TUBE.

The erternal torm of the tube is extremely" variable. The main factors affecting the external form appear to be the extent of crowding, and to a lesser extent the nature ot the substratum. Exposure to wave aotion does not appear to have an influence on the struoture ot the tube. It appears, however, to be intluenced by the chemical oonditions of the water, sinoe those tran the muddy upper reaches of r,ttelton Harbour differ oonsiderably fraa those tound on the open coast.

Where the tubes are found singly they are more or less triahgular in cross-section with. a ridge or keel, developed to a varying extent, on the upper side. In some spec~ens the keel is sharply pointed in others, partioularly in some trom Auckland, it is broad with a sharp ridge along eaoh side. Anteriorly the keel ends in a point pro3ecting above the opening. The development ot this projeotion is also ertremiJ7 variable and it may be entirely absent. Externally the tube has the appearance ot being composed ot a series ot sucoessive rings. This ringed appearance again is more developed in some looalities. It is very pronounced in speoimens trom the upper end ot ~telton Harbour. Tubs trom this locality are also enormously eDiarged, being about twice the average length and thiokness ot those trom the open coast. .The water in which they develop is always turbid and the ditterence may be correlated with the chemical oonditions ot the water.

On the coasts ot Banks Peninsula two markedly ditferent growth torms ot the tube oocur. Where the tub es are growing attached to rook and other solid substratum they have the appearance outlined above. In such cases the tube is otten incomplete ventrally, the rook surtaoe completing Uhe tube. The tubes are usually" curved in one or more direl tions and may be part~ attached to the substratum and partly tree. The direotion ot growth ot the tube does not appear to be correlated with any struotual peculiarities ot the substratwn., and does not appear to be influenced by light or gravity. Be­sides growing attaohed to rook surtaces tubes have been tound growing on the shells ot the tollowing molluscs, Mltil ... s canalioulus, MRilUS ;planulatu8, AlIlaCOUfa maorica, Wsia hiustrUDl, LUne a smagrada and Gadlnia n vea. -

Under oertain conditions the tubes ot Pomatoceros torm huge enorustations ot closely" intertwined tubes growIng

Fig. 18.

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Photograph of a ub Lyttelton Harbo growt Ii es.

X I~

from the p e end 0 sh ing ell marked

t gra h sb~Ning the variable of the ventra collar fo d. on th lett are from the cl05 encrustations , thoe on the right f 0 the u per end of Iuttelto Bar our.

- 19 -

out tram the rock surface for a distance of up to eighteen inches. The tubes forming these masses are cylindrical in shape, the torsal keel and the anterior projection being extremely reduced. fin some cases the keel is reduced to a fine raised line which winds round the tube in a spiral, indicating that the position of the warm within the tube has altered as secretion bas taken place; in others it has dis­appeared completely. A structural modification of the ventral collar fold is correlated with the reduction of the keel. The long triangular pointed flap on the ventral collar fold is absent (Fig. 19. ). The tubes are extremely thin and brittle; a slight pressure of the fingers being sufficient to cause them to collapse. Some of the tubes have been traced back into the tube mass for a distance of 'taB inches. Below the occupied tubes on the outer surface the empty tubes are packed with sand, shell grit etc., fOrming a cement-like mass. larvae settle between the outer ends of the tubes and numerous small tubes are found attached to the older ones. As development proceeds these tubes grow outwards. Under such crowded conditions there will be intense campetition for food, since those tubes which project furtherest are in a mare favourable position to obtain food. The great increase in the length of the tube that results leads to the extreme thinness of the tubes noted above. The appearance of the tube mass from the outer surface is that of a large number of closely packed cylinders. (Fig. 20. ). ' This arrangement would enable the tubes to withstand wave action in spite of their extreme thinness.

The calcareous tube has a transparent, tough, gelatinous lining. The majority of tubes contain a Tariable amount of blue pigment in their inner walls. This is apparently added after the tube has been formed, as newq :rormed tube is invariably white. In same tubes, especa 117 in the oyl1n4rical tubes of the enorustations, the pigment may be entirely absent.

To determine the internal structure of the tube small pieoes were mounted on a slide with pre-heated Canada Balsam and thin sections prepared by the method used for the preparation of geological specimens. One side was ground smooth on a glass plate, usine emery powder of successively finer grades (120,220 and 3 F), the seotion removed, inverted and the grinding repeated until the tube was sufficiently thin. Longitudinal seotions showed that the tube was com­posed of sucoessive rings of oaloium carbonate. When pre­paring the thiok triangular tubes for sectioning, it was :round that a series of spaces extended along the length or

Fig. 20, ew of the ends of the tubes of the Poma­toceros e crustation showin the a sence of t e projecting spines.

ction of t tbe wall. Hot

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- 20 -

the tube on each side, in the lower corners of the triangle (Fig. 21). These spaces are rather irregular in shape; but appear roughly triangular in cross-section, with the base of the triangle towards the substratum. Similar s~ces are reported in Pomatooeros trigueter (MoIntosh 192~) and in such Serpulids as Vermillopsis and pamatost~us (Flauvel 1927). These spaces are probably left to econ ze the amount ot material used. When examined under the microscope the sections of the tube are seen to be penetrated by fine canals. These are formed by only certain ot the collar cells secreting calcium carbonate. .

It the tubes are placed in dilute acid the calcium carbonate is dissolved and a considerable amount of organic residue is lett. This consists of an inner cylindrical tube with a mass ot loose fibrous material surrounding it. The latter is the organic base in which the crystals of calcium carbonate are embedded. When examined under the microscope it is seen to be composed of two types of material, flat transparent sheets and long fibres. These stain meta­chromatically with methylene blue, the former purple and the latter blue. The organic residue also shows positive stain­ing reactions with the following mucus stains, muci-haematin, thionin and tolu.din blue. A positive colour reaction was obtained using the xanthoproteic test and Millon's reaction tor proteins. The material is theretore a glycoprotein of a mucoid nature.

The Mineral Character ot the Shell.

Clark and Wheeler (1922) have made several determin-ations of the oomponentelements of Serpul1d tubes. They tound that they oonsisted mai~ly of calcium carbonate with small amounts of magnesium carbonate and traces of phosphates and sulphates.

The calcium carbonate crystals torming the tubes ot Serpulids and other oalcareous structures in invertebrates .. such as molluscan shells, are either in the torm at calcite or aragonite. Oalcite is the hexagonal torm ot caleiua carbonate, and aragonite the orthorhombic torm. Various standard Mineralogical tests were used, with powders ot the known minerals as controls, to determine the torm present in the tubes ot Pamatoceros, viz:-

(i) Meisen's Reaction (Holmes 1921, p 262), con­Sisting of bOiling powdered material with Cobalt nitrate.

v€

Photon crograph of a section passing through the base and the outer end of th ventral collar fold.

- 21 -

Powdered tube material gave an immediate violet oolouration, indicating the presenoe of Aragonite. Powdered calcite gave no reaction.

(ii) Fie,\&'S Test (Fie~l 1939) oonsisting of test­ing the material w th a solution of manganous auJphate contain­ing silver sulphate. A black precipitate was formed within two minutes, indicating the presence of Aragonite. Bray (1944) has shown that the above taste are not conclusive sinoe impurities of magnesium oarbonate affect the reactions; so the following confirmatory test was carried out.

(iii) ~sical determination E[ specific gravity; calcite has a sp~f!o gravIty of about 2·~and aragonite about 2.9. The tube to be tested was boiled in strong potassiwn hydroxide to remove all the organic material, washed and drted and plaoed in a test tube, in whioh a density diffusion column had been made by adding gently a few drops of carbon-tetrachloride to bromoform (S.G. about 2·9). Small pieces Yof known oeloite and aragonite were added. These remained suspended at their appropriate levels and the addition of tube fragments enabled a determination of their nature. The Aragonite nature of the tube caloium carbonate was confirmed. This determination agrees with that found by Potts for Pomatpoeros trigueter (Robertson and Pantin 1938).

(ii) TUBE FORMATION.

(a) Histology ~ the Oollar.

The dorsal epithelium of the collar consists of a single-layered epitheliwn of unciliated oolumnar cells ~th a thick cuticle. Towards the outer edge of the collar the oells beoome shorter and the outicle thinner. Large round nuolei are situated towards the distal ends of the cells. The base­ment membrane is ill-defined and longitudinal muscle fibres run between the bases of the cells. There are no gland cells within this layer.

The oells forming the epithelium of the ventral surface are extremely variable in size and shape. Towards the edge of the oollar folds the oells are roughly oubical and stained darkly with Delafield's,having the appearance of being paoked with roundish granules. The collar is muoh thioker at the base than at the tree end and between the two layers of epithelia there is a broad band of loose connective tissue often containing large spaoes. Numerous blood vessels run among the connective tissue and extend up between the

-.22 -

epithelial cells of the ventral surface, until in same places they lie immediately underneath the cuticle. Thus the majority of the epithelial cells are in direct contact with the blood vessels. The epithelial cells of this region vary considerably in size and shape. A large proportion of the cells are of a glandular nature and are much elongated, extending well down into the connective tissue, the basal ends often being swollen. These cells stain faintly with thionin; but give no staining reaction with other mucus stains. The two layers of epithelia stain differently with Mallory's, the dorsal staining red and the ventral yellow. Some· of the gland cells show material being extruded through the cell surface to the exterior.

At the bases of the collar folds, where they tuae with the peristamial segment and on the dorsal and lateral sur~aces of this segment, the greater part of the epithelial .. 118 are mucus-gland cells (Fig. 25). These mucus cells ar. SOI!18What elongated and their inner ends may be swollen. They giv~ intense metachromatic staining with the specific mucus stains, muci-haematin, toluedinblue and thionin.

(b) Presence of calcium within the cells 2! the collar.

various attemp'ts were made to determ.1ne the dis­tribution of calcium in ~he colier ana o~ner regions of tne bodT. In making histological preparations care was taken to avoid acidity and the consequent solution of the caloium, neutral formalin and alcbhol being used as fixatives. Seotions were stained by Von KOssa's silver nitrate method and with alizarin S. A positi~e reaction for calcium was obtained only in the cells lituated in the ventral epithelium ot the collar. It is this Surface of the collar that is in contact with the outer rim of the tube when the oollar is rolled back over the opening.

(c) Method S!! ~ formation.

The collar fold is generally yellowish in colour, being somewhat transparent, with the greenish blood vessels showing through. If the worm is removed from its tube the collar folds lose their transparency atter one to two hours, and gradually become whitish in colour, due to the formation of oalcium carbonate within the gland cells of the collar. The whitish appearance sometimes is found in specimens still within their tubes, apparently in the process of adding to their tubes. Removal trom the tube acts as a stimulus for the fo.r.mation of calcium oarbonate. This stimulus acts directly on the cells concerned and not through the nervous system, since, if small pieces of the collar folds

- 23 -

are removed and placed in sea-water the ~ormation of calcium carbonate within the cells still occurs.

Small pieces o~ the whitish collar ~olds were removed and mounted under a microscope. Under low pow~ the collar appeared to be full o~ large,oval, whitish concretions. With higher power it is seen that these are cells packed full o~ whitish granules. I~ pressure is applied to the cover-slip and the cells separated the oval out­line o~ the cells containing the granules, can be seen. The cytoplasmic contents o~ these cells stain int.nsly with intra­vitdm. stains, methylene blue, nile blue and neu..tlril red. I~ dilute acid is run under the cover-slip the granules gradually disappear and bubbles of gas can be seen, indicating that the ~anules are calcium carbonate.

As mentioned above, removal ~am the tube is a stimulus ~or tube ~ormation and worms removed from the tube begin to make a new one wi thin a ~ew hours. When removed the collar folds roll back over the ventral and lateral surfaces of the thorax and secretion takes place into the space thus formed. The first ~ormed sec~.ti&n is of a transparent mucoid nature, sinoe it stains readily with mucus stains, thionin, tolu din blue and muoi-haematin and is probably derived trom the mu~gland oells situated at the bases of the collar folds. on the ventral and lateral surfaces of the peristomial segment, as no true mucus secreting cells have been detected in the collar itself. Later this secretion turns white due to the crystallization of oaloium carbonate seoreted by the collar gland cells.

Fauozi (1930-31) described the attempts Pomatoce ros ~riqueter made to form a tube and they have been brietly redescribed by Thomas (1940). The observations made on Pamatooeros coeruleus agree in the main with the descri~ion given by Thomas. The tube is first formed in three separate pieces, a spur-shaped piece in the ventral fold and a lateral plate in eaoh lateral fold. These later join to form a single piece of tube which gradually increases in size. Hcw­ever'. the worms are unable to form a complete tube, since they are unable to oomplete the tube dorsally, due to the lateral collar folds not overlapping as they do in the worm wit~n the tube. Also the movement of the worm displaces the pieces of tube as they are formed.

(d) Method 2!. Deposition 2!. !!!! Tube Material.

A great deal o~ work has been done on the method of deposition of the shell in molluscs; but as yet, practically no work has been done on the method of tube deposition in

- 24 -

Serpulid worms. Hansen (1948) states: "The Dew tube f1 rst appears on the ventral surface of the anterior part of the thorax under the ventral collar fold. It is not known how this new tube is formed; but it seems likely that it is secreted by glands in this part of the thorax." . There is general agreement that in molluscs calcium carbonate is separated from the blood by certain cells of the mantle edge. The same process ~robably occurs in the collar region of Pamatoceros coeruleus, linca the blood supply to the gland cells is partIcularly well deyelpped, although the possibility ot the direct uptake of calcium from the surrounding sea-~r by the cells is not eliminated. Within the oollar gland cells are for.med spherules or granules of calciumoarbonate .nich pass through the cuticle, probably in a colloidal form, and mix with the secretion fram the mucus-gland oells. Crystallization trom this colloidal gel then takes place ertracellular17. The colloid may be transforaed into tube material either by enzyme action, or by a physico-chemical reaction t or by a caa~ation ot the two. The enzyme alkaline phosphatase which is concerned in the caloification of bone has been found in the mantle of molluscs and in the oollarc region of Pamatoceros trigueter b.J Hansen (1948). It has been concluded that it is in some way conoerned with the process of shell formation in molluscs and tube formation in Serpulids. Since the enzymeiis specifically concerned with the formation of calcium phosphate it is difficult to see the part it could play in the formation ot calcium oarbonate; unless as has been claimed by Plate (1922) for molluscs the calcium is first secreted as phosphate and later changes to carbonate. There is little evidence in support of this viewpoint.

The conilusion that the collar region is responsible for the formation ot ,the calcium carbonate is supported by experiments in which portions of the collar were removed~ Worms in which the entire collar had been removed showed no signs of tube formation after several weeks; while those in which the ventral or ,lateral folds had been removed formed small pieces of tubes in the remaining tolds.

(e) !!!:!. Deposition !r! Arasonite.

A further problem in the secretion of calcareous tubes and shells is raised by the occ~e of the different forms of calcium carbonate, calcite and aragonite. So far no adequate explanation can be given for this difference. Trueman (1942) has suggested that the presence of other minerals may influenoe the form of the calcium carbonate. ClaDke and Wheeler (1917, 1922) tound magnesium, in varying amounts in many calcite shells; but never in aragonite shellS..

- 25 -

In the Serpulid tubes that they analysed, they found magnesium present in all but one species. The torm ot the calcium carbonate in the tubes they studied is unknown, and a determination ot this as well as the presence ot other substances in the tubes ot various species of Serpul.1d would be interesting.

(t) Origin £! !B!Shell Material.

Studies carried out on molluscs have led to the conclusion that the greater part ot the calcareous material of the shells is probably absorbed dimectly tram sea-water as calcium and bi-carbonate ions. Metabolic carbon dioxide, however, will be the primary source of the carbonate radicle. In the present investigation experiments pertormed with Pomatoceros coeruleus lead to the same conclusion, and other indirect evidence suppor~s this conclusion. Experiments carried out were similar to those pertormed by Potts (Robertson ~nd Pantin 1938).

Worms were placed in art1'icial sea-water made aoeording to the tormula ot trman and 71em1ng (Harvey 1945) and these commenced tube tormation as usual. Others were placed 1n calcium-tree, artificial sea~ter in which they lived tor a short ti.e without commencing tube tormation. The non-production ot tube material, howeTer, :may be due to tactors other than the lack ot calcium in the sea-water, as the possibility of stored calcium in the blood is not eliminated. Robertson (1941) has pointed out the importance of calcium in regulating the iaDic permeability ot cells and in the stabilization of' m\lcas6 coverings. lience calcium-tree sea-water would tend to disperse the mucoid secretion. Robertson (1941) has analysed batches ot Pamatoceros trigueter betore and atter oalcareous seoretion has taken p18ce in filtered natural sea-water and the results demonstrate the up-take of calcium trom sea-water.

The possibility still remains that the calcium may still be largely obtained tram the tood and other ingested material, including particles ot shell. Circumstantial eTidenoe is opposed to this possibility. Fox and Coe (1943) working on molluscs have estimated an annual intake ot 91,250,000 dinotlagellates per mussel.. It these organisms contain about 0-43 10 ot caloium, as has been determined by the calcium-nitDcgen ratio ot various analyses, they oalculated that the annual intake ot dinotlagellates would provide a 100 m.m. mussel with only 0·062 gill. ealcium in a year. The organic matter in the diatoms and other organisms consumed

26 -

inoluding detritus would contain only a fraction of a gxam more. The food of Pomatoceros coeruleus is somewhat sDnilar and the annual intake of food would only be a fraction of that of a mussel. Sinoe an average length tube contains over a gram of calcium it clearly could not have been obtained from thee:f'ood.

There is considerable reason to believe that the greater proportion of the calcium must be taken direotly fram the sea-qter. When the worm is protruded arconstant stream of water passes through the gill-filaments. FoX', Sverer up and Cunningham (1937) have shown that a mussel would on17 require to utilize one fifth of one per oent of the calcium in the water passing through its gills in a year to obtain seventeen grams of oaloium. Potts (Robertson and Pant~ 1938) found that Pamatooeros t~i9ueter would go on forming tubes when plaoed in ffiitlafai sea-water containing half the normal quantity of caloium per litre. Thus the amount of oalcium in normal sea-water is olearly more than adequate.

A third source of oalcium consists of minute particles of 4111niegrated shells of mollusos and barnacles and calcareous tubes of this and other species of Serpulid and oalcareous algae. It is possible that a large proportion of the calcium utilized in the formation of the tube is obtained from partioles of the ~bove ·~terial which are taken into the dilesti va tract. .. Information as to the pH of the intestine would be needed to see if it were sufficiently aoidio to dissolve the partioles.

(g)G _r~awt;;.;..;....;.h;.;. 2! the Tube.

Sergrove (1941) has studied the early development of the tube of Pamatoceros trigueter. He found that when the tube is first tormed It Is semi-transparent and appears to be composed of mucus partly impregnated with calcarous matter. It is open at both ends and initially much shorter than the body. The tube increased rapidly in length at a far greater rate than the body. Dons (1927') found that the permanent tube was built as a continuation of the first-formed temporary tube which soon dissolved. He found an approximate gtowth rate of 1·· 5 m.m. per month.

Speoimens of Pomatoceros coeruleus added 2 m.m. of tube while kept in an aquarium fl)r two months. Often 1h e anterior portion of the tube, varying in length from 1 m.m. to 3· 5 o.m. is much whiter than the rest, with a fair ly sharp

(ho

Photograph showing repair to a broken tube .

....... .... . ,',I '

' , ' :: : ', ' ' .. , ..

he post rior e calc r 0

~f a roke tu e ~ owing plate .

- 27 -

damartation between the two. Thus it appears probable that the secretion of the tube material is intermittent and probably seasonal. The marks on the older parts of the tube are obliterated; but it is probable that they are four to tive years old.

ExPeriments were carried out to determine to what extent Pomatoceros ooeruleus was' capable of repairing damage to the tube. Portions were removed fram the anterior abd posterior ends. of the tube, tubes were broken in half and pieoes removed at various places to expose the worm within the tube. It was found that the broken halves were joined together and the .openings were covered by a tough transparent membrance, similar to the lining of the tube. The material for repair is probably derived fram the numerous mucus glands of the parapodia. Rings of tube materials were also added to tubes in which the anterior end had been removed. In one tube in which a more or less hem1-spherical piece had been removed the worm added a creDentric shaped pieoe (Fig. 23) to repair the damage. This indioates that the collar is capable of differential secretion, since secretion took place in one region only.

In those worms in which the posterior end of the tube had been removed it was found that after several days the posterior end of the tube had become blooked by a calcareous plate. These plates (Fig. 24 ) are inolined at an angle, grooved down the mid line and appear to have a series of 'holes' along each side. As in the normal tUbe formation this plate is precede.d .. ~ bJ'. a mucoid membrane which later beoomes calcified, except for the series of eniptioal areas along each side. Thus the'hole~are oovered in life by a thin membrance which disappears in old empty tubes. Similar structures have been reported in Pomatoceros 'brigueter by McIntosh (192") and Thomas (1940).' Their development does not appear to have been followed.

If the anterior end of one ot these plates is examined, it is seen to be concave with a series of depressions ending in the 'holes' covered by a transparent membrane. When the worm is in the tube the poaterier end of the abdomen, whioh is tlexed dorsally, tits into· the concavity. The ventral gland shield areas of the posterior segments fit into the series of depressions on each side. Muous gland cells are particularly well developed in these posterior segments, being mare on the anterior abdominal segments. Also the blood supply to these posterior gland shields is especially

- 28 -

well developed. By follOwing the development of these plates it oan be seen that they are formed from seoretions of gland oells looated in the ventral gland shields of the posterior segments. Apparently the exposure of the posterior end of the worm is the stimulus for the formation of these plates. They are found, however, in the posterior portion of tubes whioh have not been brOken. Suoh plates have only been found in tubes over ~ ~. in length; never in short tubes. On oooasions in the very long tubes two or even three suooessive partitions are found. It would appear that in the very long tubes the diff~eulty of maintaining the oiroulation of the water within the tube promotes the seoretion of a partition.

SUMMARY. The tube of Pomatooeros ooeruleus is oomposed of a glyooprotein of a muooid nature, in whioh orystals of oaloium oarbonate in the form of aragonite are deposited. It is formed as a disoontinuous seoretion from. the gland oells of the oollar region of the peristomial segment. Only one other region of ilhehbody is oapable of suoh seoretion, viz. the posterior segments which seorete partitions dividing off the posterior end of the tube. The evidenoe so far oolleoted points to the sea-water as the souroe of oaloium in tube building.

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- 29 -

9. THE MUSOLATURE.

The general f'orm of the musclature in the dit~ regions of' the body oan be seen in Figs. 14, 2;, & 26.

(i) MUSOLATURE OF THE BODY WALL. -. The oiroular muscle layer is poorlY' developed:l

Pomatooeros ooeruleus, as it appears to be in the majori" of tUbicoious poliohietes. It consists mainlY' of' isolat f'i bres lying immediatelY' underneath the epidermis. In ti thoraoic region, particularl1 at the anterior end, there e well-marked vertical bands of' f'ibres, lying between the epidermis and the underlYing longitudinal muscles •

. The longitudinal muscle f'i bres are grouped into zones or bundles of whioh there are eight in the thoracw region and three in the abdominal. In the thorax there is , pair of' dorsal lossitudinal musoles .~ending well down en either side of' the coelom. At the posterior end of' the thorax they unite to f'orm a single medilP dorsal lonsitudinal muscle which extends to the posterior ena ot the worm. The lett ~orsal longitudinal muscle is continu~d into the operculum as the opercular muscle and the right is inserted beneath the thiok epithelIum at the base of' the brIDchial crown.

There are a pair of' lateral lOngitudinal muscles attaDhed to the dorsal epithelium ot the peristamIal segaent and extending posterierly, between the lateral epithelium and the nephridium. The vertioal height of' these muscles increases as they pass back and they end at the posterior end. of' the thorax. In the ventral region of' the thorax there are a pair of' ventral thoracic lonsitudinal muscles, inserted beneath the epithelium 01 the prostomIum and extending back to the posterior end of' the thorax on the median side of' the ventral nerve cords. At their anterior ends these muscles are circular in oross-section; but posteriorly they 11att en out and gradually decrease in size. In the second segmEnt another pair of' muscles the ventral longitudinal muscles are inserted on the ventral epithelium beneath the ventral nerve oords. As they pass back they increase in size and came to lie laterally to the nerve oords whiCh lie closer together in the abdominal region. In this latter region they increase in size and f'orm the only longitudinal muscles in the ventral side ot the body.

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Obl~ue muscles are absent except ~or a single pair in the ~irsto se~ents. They are attached to the dorsal epithelium, laterally to the dorsal longitudinal musoles and pass oblique~ on the inside o~ the nephridia to the ventral bod7 wall.

The longitudinal muscles are very well developed, being grouped to ~orm large well-de~lned muscle bands adapted tor quiok oontraction into the tube. At the anterior end ot the bod,- the epithelium is enormous17 thickened in order to provide a ~lrm attachment tor these muscles.

(li) BRANCHIAL MUSCLA'l'URE. I

A pair o~ obllgue branohial auscles originate beneath jlhe thiokened epithelium. fateraII,- to tJie aorsal longitudinal musoles in the seoond se~ent. These pass round on the outer side ot the base ot the branohial crown beneath the epithelium. Contraction o~ these musoles oause the opening out o~ each halt ot the branohial orown. On the inner side ot the coelomio space. in the base o~ the branchial orown, lie a pair o~ branchial musoles inserted together onto the epithelium where the inner sides ot the two halves o~ the crown 1mite. These muscles are ~ormed trom the union ot the paired internal branchial musoles 17ing on the inner corners o~ the filaments. The paired external brancial muscles on the outer oorners at the tilaments end beneath the epithelium at the bases ot the ~ilaments. The contraotion o~ the internal muscles causes the tila:m.ents to ourve inwards and that o~ the external muscl. oausea them to ourve outwards in the position assumed when ~eeding. The movements o~ the pinnules is at~eoted by the pinnule lO~itudinal musoles whioh lie underneath the oiliated oells ot t e plnDuies. Contraotion ot these muscles cause the pinnules to bend in towards each other.

(1 v) MUSCLES OF THE COLLAR AND THORACIC Ml!HBR.A.NI.

The muscle fibres o~ the collar and the thoraoic membrane consist o~ a soattered la,-er o~ tibres, lying among the bases ot the epithelial cells on the inner side o~ the membranes. They run trom. the bases ot the membranes to the tree end.

- 31 -

( T ) C1IA.:I'16L MUSCLES.

The long .baetae ot the thoracic neuropodia are embedded in the ahaetal sacs which extend about halt the depth ot the thorax. The extensor muscles consist ot two groups, an outer and an inner group, running trom the body wall to the ventral end ot the sac. The inner group is attached to the dorsal epithelium; while the outer is attached to the epithelium ot the notopodium. On the ventral ends ot the

, chaetae themselves there are small muscles attaching the chaetae to the chaetal eac. The retractor muscles which are not as well developed as the extensor muscles run trom the epithelium to the more dorsal regionot the sac. Movement ot the chaetae in various directions is brought about by the contraction ot the approp~iate extensor and retractor muscles. The uncinal muscles consist ot a single muscle attached to each uncinus and passing to the anterior epithelium ot the neuropodium.

The arrangements ot the muscles in the abdominal parapodia are essentially the same except tor the reversal ot the position ot the long chaetae and uncini.

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- 32 -

10. AIJ"MENTARY SYSTBM •

( i ) ANATOMY •

The alimentary canal ot Pomatoceros is a simple tu 'I:B without diverticular or convolutions ot any lind. Histologic­ally the alimentary tract can be divided into tive regions: (a) The buccal cavity; (b) the oesophagus; (c) the stomach; Cd) the intestine; C.) the rectum.

The buccal cavity tormed by the dorsal and ventral lips .i8 crettentric in cross-section - the concave side being dorsal. Posteriorly the buocal cavity passes gradually into the ·oesophagus, (Fig. 27) which passes ventrally. At the anterior end the lumen is broadly oval; but posteriorly it becomes slit-like, with the greatest di~eter horizontal. and betore opening into the stomach circular. -The epithelium lining the oesophagus is ciliated and longitudinally tolded. The whole ot the oesophagus is surrounded by a blood plexus ljtng in connective tissue. Internal to the plexus there is a well-developed layer ot circular muscle tibres.

At the posterior end of the second segment the oesophagus opens into the stomach. '!'he opening is narrow and the .anterior end ot the large stomach bul~ torward round tie posterior end ot the oesophagus. . The cilia at the junction in both the stomach and the oesophagus are very much elongate~ The walls ot the stomach consist typically ot three. layers: (a) A Dlusculo-epithel1um, containing muscle tibres arranged transversely to the long axis ot the stomach; (b) a vasoular sinus surroundins the gut. bounded on its inner side by an endothelium; (0) a ciliated and glandular epithelium resting on a well-detined basement membrane. The histological details ot the walls ot the gut sinus will be described in detail and discussed in the section on the Blood System. In transverse seotion the stomach torms a pOinted oval with the greatest diameter dorso-ventrally. The epithelium is tolded towards the ventra-I surtace.

At the posterior end ot the thorax the stomach passes into the intestine which is rounder in transverse section than the stomach. '!'h~ walls ot the intestine have the same general structure as those ot the stomaoh. The intestine narrows posterior17 to torm the reotUJll, which ocoupies- the last t8fl segments. In this region the walls are much tolded and muou .. gland cells are extremely abundant.

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- 33 -

(ii ) HISTOLOGY.

(a) Buccal oavity.

The histology of the buccal cavity has been desoribEd in oonneotioBwith the branchial crown.

(b) ~ oesophagus. (Fig.30).

The epithelium of the oesophagus rests upon a well­defined basement membrane. It is similar in appearance to that lining the buccal oavity; but the cells are more elong­ated, varying in height, giving the walls a folded appearanc~ The cells oontain a granular rather darkly staining cytoplasm. Between the distal ends of the cells are abundant globular or pear-shaped mucus-gland cells. Oval nuclei lie at the bases of the epithelial 8ells; but none has been observed in the mucus-gland cells.

(c) The stomaoh. -The cells of the epithelium appear to exist in two

physiological states, the majority of the cells in one region being either ciliated or secretory.

The ciliated cells (Pig. 28 ) are very tall and narrow with oval .uolei lying towards the distal ends of the cells. The cytoplasm is granular, the distal ends ot the cells staining more darkly with haematoxylin and Mallory's than the rest. Towards the bases ot the cells are spherules which stain darkly with laematatylin. Brazil (1904) has described similar structures in various Polychaetes as degenerating nuolei. The cells are uniformly covered with short oilia arising trom bassI granules Just beneath the outer m~brane of the oell. The basal rods are thus extra­cellular and the ooagta.m surrounding them gives the appear­ance of a thick cuticle.

In various regions of the stoinach there are patches of non-ciliat.a gla~dular oells (Fig.29). These cells are club-shaped with the rounded endprojeoting into the lumen of the gut. The nuolei are oval, showing a large nucleolus and are situated about half-way aloD&?~h8 oells. In the pro­jecting tree ends of the cells large clear globules of seoretory material can be seen. 'Within the gut lumen and clustered round the ends of the seoretory cells are numerous round globules which are seen issuing tram the club-shaped ends of the cells. These globules stain an intense yellow

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- 34 -

with Mallory's and pink with Mann's double stain. In sections stained with Mallory's same o~ the seoretory cells are stained yellow, others having the proxtmal end red and the distal yellow. When the gland cells commence seoretions the globules are.pushed out under the cilia whioh are oarried out and apparently shed; as a layer o~ secreted globules oan ofien be seen between the cilia and the ends o~ the cells. No oilia are 'to be seen when the cells are in an advanoed stage o~ secretion. The above method o~ seoretion is very similar to that reported by Niool (1930) ~or Sabella pavonia.

(4) ~ intestine4 (Fig. 31).

The epithelium lining the intestine consists o~ oolumnar ciliated cells whioh vary oonsiderably in height. The cytoplasm. o~ the cells is ~ll o~ granules which stain darkll' with haemato:zylin and towards the distal ends o~ the oells the granules are very ~ine and closely packed. There is a band o~ oval nuolei lying underneath the dense layer o~ cytoplasm. In addition to this band o~ nuolei there are other de~se nuclei scattered in the basal portion o~ the epithelium.

(e) ~ .. re;;;;..:c;.;;:t_UDl;;;;;..

The rectum is distinguished trom the intestine by the presence o~ numerous mucus-gland cells. These cells become more abundant towards the anus. Between the mucus­gland oells are narrow cells bearing strong cilia.

_F~iS~.~~;~2~. A terminal view of the branchial orown with the filaments fully spread, to show the collecting tracts of the filaments and lips.

- 35 -

11. FEEDING.

(i) METHOOO.

For the purpose of determining the oourse of the oiliary ourrents of the branohial region oarmine powder, starch grains stained with iodine and various grades of oarborundum were used. The observations were made with a binooular miorosoope, the worms being kept as far as possible under natural conditions. Suitable specimens were placed in a jar of sea-water and suspended in any desired position by means of fine wire. Observations were confirmed on worms removed from their tubes, and the finer details of the cilialY traots were determined by removing parts of the branchiae and eXamining them under higher power.· Specimens were found l~oking blue pigment on the lower half of the branohial filaments and these proved very useful.

(ii) COLLECTING CURRENTS.

When feeding commences the anterior portion of the body is protruded from the tube and the branchial crown expanded. The degree of expansion Yaries from individual to individual. In an average speoimen the two halves of the branchial crown are drawn apart, the individual filaments . ourving outwards to form a shallow funnel. The two rows of pinnules make an angle of about 1200 with each other, inter­looking with those of adjaoent filaments at the base; but lying tip to tip towards the distal end (Fig, 32 ).

Water is drawn into thefunnei by the aotion of the latero-frontal oilia (Fig. 33b) which beat strongly at right angles to the longitudinal axis of the filament. This water current oarrying suspended plankton and detritus passes through the network of pinnules. These partioles are entangled in mucus secreted by the glands in the pinnules and are oarried to the filaments by the aetivity of the frontal oilia. As Nicol (1930) has pointed out in Sabella pavonia the collection of particles is partly brougbtabout by an eddy formed in front of the pinnule by water flowing past at the sides. This forms a region of reduoed pressure carrying an inflow of water trom the sides bearing suspended particles. The particles are carried down to the gill folds by the oilia lining the filamentar groove.

The gill folds are arranged in pairs with their inner faces almost touching. These folds are ciliated on

Fig, 3Ja. A terminal view of the branchial crown with --=~-........ ~ the :rilaments fully spread, to show the

rejection tracts or the filaments and lips,

- 36 -

their inner faces and outer ends. large particles are prevented from entering the gill folds and are oarried up by the oilia on their ends and along their edges to the free edge of the ventral lip. Fine particles pass down between the gill folds to the groove between the ventral lip and the lower ends of the filaments. Here a current carries. the partioles into the mouth (Fig. 32 ).

( iii) REJEOTION OURRENTS.

The large particles whioh are prevented fram entering the groove between the ventral lip and t'he gill fil~ents are carried along the free edge.of the ventral lip and on to the inner edge of the palp. They travel along the palp to the tip and pass out with the compensating outgoing current of water in the middle of the branchial funnel, caused by the wetel:' drawn in by the latero-frontal oilia. The particles which pass on to the palp' are usually embedded in mucus to form a string or rope of matel:'iel.' If large masses of material such as e thick suspension of carmim pass in between the gill filaments, copious quantities of mucus are secreted forming thick strings which are carried away by the outgoing current. (Fig. 33).

Sometimes food material whioh has passed in between the dorsal and ventral lips is thrown out again. This would seem to indicate that the cilia on the inner surfaoes of the lips can reverse the direction of their beat. Faeces and any debris that may accumulate within the tube are oonveyed by the oilia lin.ing the ventral ~oove to the posterior end of the thorax, where two ciliated tracts lead round each side to the dorsal surface of the thorax. The cilia here, in the angle between the thoracic membrane and the dorsal wall, beat forwards carrying the material on to the dorsal lip, where it travels up the inner side of the ciliated ridge (Fig. 13 ) leading on to the palp, along whioh it follows the same path as the material rejected from the branohial crown.

( 1 y) NATDRE OF THE FOOD.

Theoontents of the digestive tract of various worms has been examined. From the nature of the food oolleoting meohanism it is clear that the food must be very finely divided matter in suspension in the water. Hunt (1925) ex~ined the gut contents of various cryptocephalous Polychaetes and found that the food consisted of very finely divided

Fig. 33b,~A diagramatic section of two gill filaments to show the direction of flow of the water entering;the branchial funnel (indicated by the large arrows) J and the direction of the beat of the cilia (indicated by the small arrows,)

- 37 -

plankton and detritus. EX8XDination of the gut oontents of Pamatoceros ooeruleus show that its food is of a similar nature consistIng prIncipally of:

(1) phytoplankton, including particularly diatoms as well as other algae, algal spores, dinoflagellates and bacteria.

(2) Zoo-plankton, including flagellates, oiliates, and tintinnids.

(3) Invertebrate OTa and spermatazoa.

(4) Organic detritus, mostly unidentifiable but including chloroplasts, fragments of algae and disintegrated cells of plants and animals.

The most ~portant constituents Of the food appear to be diatoms and organic detritus.

(v) T1WQ3PORT OF FOOD ALONG THE GUT.

The altmentary canal is ciliated throughout its length, the cilia at the junotion of the oesophagus and the stomach being particularly long. These lone cilia can be seen to fill the lumen (Fig. iA,1J • Hansen (1948) has discussed the transport of food in aquatic annelids and observations made on Pamatoceros coeruleus confirm her main conclusions.

The only muscle coat of the alimentary canal lies outside the blood sinus. These muscles contract anti­peristaltically moving the blood forward along the sinus. This would tend to hinder the passage of food. The cilia lining the gut beat in an antero-posterior direction and it is the action of these cilia that transport the food boli along the gut. The boli rotate in a clockwise direction as they pass down the gu'b-.

(vi) DISCUSSION.

Orton (1914) has discussed briefly the feeding mechanism of the cryptocephalous Polychaetes and Nicol (1930) has compared that of Sabella pavonia with other Polychaetes. Throughout the Sabelll-i'orDiIa the ciliary feeding mechanism is essentially similar. The Sabellids differ trom the Serpulids in that they possess an additional set ot current prDducing cilia, the abtrontal cilia. As pOinted out by

- 38 -

Niool (1930) the oompound latero-trontal oilia, which oarry the tood particles on to the trontal oilia are similar in struoture and funotion to the latero-trontal cilia 01' oertaiil Lamelli-branchs such as Mytilus and cannot be compared with the lateral cilia of other Lamellibranchs, Brachiopods, Tunicates, Protochordates and certain Gastropods suoh as Cre;pidula.

When the branchial crown of Pamatoceros coeruleus is expanded the pinnules of the gill f'Ilaments lIe tip to tip forming a highly etficient mechaniHm for the filtering of tine particles from the water. The ciliary feeding meohanism of Pamatoceros is one of the most highly developed among Serpulids. In forms such as Fil06%ana implexa, there is no basal membrane uniting the bases of he fIlaments and the filamentar grooves lead directly into the mouth. From this condition a series of different speoies showing an increasing complexity in the arrangement of the food collect­ing apparatus can be traced. The number of pinnules beoome more numerous, the basal membrane becomes more highly developed and the ventral lip extends round the bases of the filaments forming a ciliated groove leading into the mouth. The sorting mechanism and the rejection tracts are ill developed in the more simple torms.

TABLE, :C. STAINING REACTIONS OF THE VARIOUS GlAND CELIS.

TOLUZDIN . MUCI-HAEMATIN MUCI - CARMINE THIONIN BM. !DEIAFIEID'S MAIJ..ORY'S MASSON'S SAFRANIN - -

BRANCHIAl. CRCWN. Pu:bple Deep Bluish Densely Densely Orange. Bluish Deep Orange. network. purple Purple. purple. green.

l network. ~

OESOPHAGUS • Dense Pink. Dense Dark Densely Reddish Bluish Deep Orange. Purple purple. Blue. purple. Orange. green. network.

STOMACH. Unstained. Unstained. Purple. Unstained Unstained Red or Red Unstained. Yellow brown.

Densely Yellowish Green. Deep orange. RECTUM. Dense Pink. Reddish Purple. . purple. orange.

purple Purple. I network.

Densely Yellowish Green Deep o~ange. PARAFODIAL. Dense Faint Reddish Dense!7 purpl~. orange. network.

GIANOO. purple Pink purple purple I network. network. network -

Densely Yellowish Green Deep Orange. VENTRAL GLAND Dense Faint Reddish Densely purple •. orange. network.

SHIELDS • purple pink. purple p\lI'ple. network. . network

Bluish Orange. Brorm. Unstained. COLIAR. Faintly Unstained. Unstained. Un- purple

purple. stained. granular.

I !

- 39 -12. GlAND AND MUCUS CELIS

The staining reactions of the various gland cells have been referred to in the sections on histology. These results are summarized in Table:J:.. There are at least three types of gland cells in Pomatoceros coeruleus.

1. The sland cells of the stomach region. These cells have granular contents tEat staIn denSly wIth different· stains. Since the cell contents gave negative results with the'specitic' mucus stains, except for a very weak staining with thionin, they are not mucus secreting cells. With Mallory's the cells are either stained an intense red or a deep yellow. Since acid fuchsion is red in acid solution and yellow in alkaline it would appear that the pH of the cell contents changes during the process of secretion. ~pherules of secreted material in the gut lumen were invariably stained yellow. Manton (1937) has noted the same differential staining in the intestinal glands of PeripAtus and Parry (1948) has found a similar reaction ib the gland cells in the mesenterial filaments of Anthopleura aureoradiata.

2. The caloium carbonate secreting cells of the collar folds. The histology or these cells has been descrIbed in the section on tube formation. These cells do not secrete mucus since their contents show no meta­chromatic staining with the 'specific' mucus stains. They stain darkly with iron haematoxylin. With Mallory's the two epithelial layers of the collar folds stain differently, the secretory epithelium staining yellow-orange and the inner epithelium red. The contents of the collar gland cells would probably be somewhat alkaline.

3. .Mucus gland cells. True mucus secreting gland cells are widely spread throughout the body of the worm, being found among the epithelial cells of the pinnules, the filamentar groove,the dorsal and ventral lips, the oesophagus, the rectum, the palps and the parapodial glands of the thorax and abdomen. with any of the fixatives used the cells show a cytoplasmic net-work. Rualei have not been recognized within th~ cells. The mucus secreted by the gland cells of the branchial region during feeding and-from the glands of the peristomial segment during tube formation show the same staining reactions as the cell contents. Sections show similarly stained secretions being discharged through the cuticle which covers the outer ends of the cells.

The theory of mucin staining has been elucidated by Lison (1936) and more recen~ly by ulara (1940) in an exhaustive treatise on the nSc~imii of human gland cells. The techniques for the detection of mucin by means of meta­chromatic staining with various stains has been developed in

- 40 -

studies on human and vertebrate histology and it is not olear how far the results obtained are applicable to invertebrates. Ewer & Hanson (1943) have compared the staining reactions of the muco-proteins of a number of vertebrates and invertebrates. They found that thionin and mucicarmine gave metachromatic staining with all the animals studied. Polychaetes, however, stained metachromatically purple with •• igert's resorcin-fuchsin and metaohromatically orange with safranin. These staining properties are not possessed by the mucp-proteins o"r most o"r the other animals studied. Pomatoceros coeruleus gave tKe srume staining reactions. Resorcin-fuohsin and safranin are basic dyes and their ability to stain certain muco-proteins is an expression of the well-known affinity of muco-proteins for basic dyes.

Clara (1940) states that mucoproteins occur as large molecular weight sulphuric acid esters with the general formula R-OS03 H which by virtue of their relatively high negative charge are stainable by the tspecific' "Schleim­farbungen," (Muci-carmine, muoi-haematin and uelatield's haematoxylim), which are positively charged when prepared and used according to the instruotions. The mucus gland cells 01' .t'omatoceros ooeruleus show intense metaohromatic staining wltq thlonin and tolutdin blue, reddish purple with the tormer and bluish purple with the latter. Accord­ing to Clara thionin and toluedin blue show "true" meta­chromatic staining only in the case 01' those "Schleimsub­stanzen" which are intensively stained with "specific" mucus stains. Lison (1936) has shovm that thionin specifioally stains polysaccharides of high molecular weight sulphuric esters i.e., mucus in a restricted chemical sense. There-fore gland cells stained by these stains can be regarded as true mucus secreting cells.

, lt was found that toluedtn blue and thionin were

useful in staining the whole worm to show the general distribution of t.he mucus glands especially the parapodial glands and the ventral gland shield areas. 'rhese stains particularly the latter, also showed the same metachromatio staining reactions when used as intra-vitama.n st.ains on the livlng worm, a dilute solution of the stain being made in sea-water.

~ot all mucus secreting veIls reacted to the "spectfic" mucus stains with equal staining intensity. Adjacent cells often showed a marked difference in the intensity of tlJ-e staining. This was particularly noticeble with tolutdin blue, where adjacent cells we~e stained either an int.ense purple ora d.ark blue. These observations shOVV' that {'mucus" in different gland cells possess different physical and. physico-chemical properties, even though th.e chemieRl comnosition m8Y show no essentiElI difference.

- 41 -

13. COELOMIC SPACES.

In the abdominal region the coelom is a spacious cavity except at maturity, when it is packed with eggs and sperms. It is divided into a series of chambers by the septa lying between the segments. In the thoracic region the sap ta run forward from their point of attachment to the body wall forming a shallow funnel. The ceelam is also subdivided into right and left halves by the dorsal and venture mesenteries supporting the gut. These mesenteries extend fram the anterior end of the stomach to the posterior end of the body. The coelomic cavities of the prostomial and peristomial segments are considerably modified. That of the peristomial segmEl'l tc' is largely replaced by vacuolated connective tis81l:8csurrounding the oesophagus. The prostamial possesses several pouch-like diverticula. It sends a pair of blind pouches running post­~riorly on the inner side of the dorsal longitudinal muscles as far back as the third segment. Anteriorly a pair pf dorso­lateral extensions pass between the dorsal and ventral roate of the oesophageal connectives. These enter the branchial base and subdivide to send branches r.unning up each of the filaments. These in turn send branches up the pinnules.

The coelomic epithelium is extremely thin and is non-ciliated except in the region of the coelomostome. ~ ventral blood vessel runs between the two halves of the v~ral mesentery and smaller vessels run bet~en the double membrane of each septum.

docs().\ \>,1 e'(c-..re\--ov-~ -" -

poce VY\ed.\ 0. V\

ex.c-ce\o'J cl.u~~~-

coe\QvV\c s.tOV'f"\e .-~ .

e)(c..ye\-or~ '::. (). c:...

~ to""" o..c..~

+\---.O",-o..c.\ c...

VY\€.W\ 'cvo..v-e

Fig. 3,. Diagram or the thorax rrom. the dorsal surface to show the position or the nephridia.

- 42 -

14. UCJ.Ut"rORy SYS~ •

(il Jl{ATOMY AND BISTO.JeGY.

Pamatooeros ooeruleus agrees with other members or the Sabellarl1dae in possessing anteriorlY a single pair or excretory nepllridia with the tunnels opening into the ooelea or the ri:rat sap-eut, and the en erDa 1 openings uniting to rOl"ll a siagle _diu dorsal pore. In the _-'orit,. or tubicolou PolYohaetes the excretory nephridia are ooD1'ined to the 8.DI;ert6:r sepents of the bod,.. This arrangement ensures that excretor,. products are eliminated without cont8ll1nating the water within the tube.

The single pair of thoracic nephridia are 'Yerr mUM enlarged, extending frca the peristomiua allaost to the poS'terlor ltRit ot the thorax (7i8. 34). ~le main bod7 of the nepbridiua which lies ventrallY in the thorax, 'between the bod7 wall and somatopleuric :atesoderm, lias the f'orm of' an asymmetrical U-shaped sharplY bent loop with the bend directed backwards. !he inner 11mb oonsists of a narrow ciliated tube opening by a wia., stronglY ciliated :tunnel into the peristomial coel_. 'file outer limb has the tora ot a wide sao, broader and deeper at the anterior end trom which a duct runs obliquelY forwards and up­wards in the anterior septum of the peristom1al segsent to the dorsal surtace. The duots form. eaeh si4& unite to tor.a a median e:roretor;y duct running forward aDd openi,ng on a SDtall pa..pilla on the anterior dorsal roof' of' the dorsal pit.

!be coelOllostOllle (Fig.47 ) bas the form of a deep ciliated tunnel on the posterior septum of the peri-stomial segment. fhe openings lie above the sub-oesophageal ganglion facing towards the mid-line. They are lined with a flat epithelium bearing long oilia. From this funnel a narrow ciliated tube runs alongside the exoretory sao, curving under­neath and opening into it ventrally, about a segment in front of the one in whioh it ends. The tube:.. is oireular in cross­section the wall being camposed of cubioal cells bearing long cilia which almost fill the lumen.

The excretory.ao (7i88.34 & 14) extends trom the prostomium to the posterior end of the thoraX. It lies between the lateral longitudinal musole of the thora:r and the peritoneum lining the thoraoio ooelom. It is separated tram these by conneotive tissue and circular musole fibres running round the sao. The anterior portion of the sac in the prostamium extends throughout the whole depth or the thorax, from the dorsal to the ventral epithelium, lying between the body wall and the longitudinal muscles. There is often an anterior projeotion into the base ot the branchial crown.

e'l.c.("'eTov'j ~ G\V"'\ I..A \ e.s

lAue..\ ev..~

(.\'("(1..;\\ o..-r VY\\Asde +, b-rc'

Fis. 35. Part ot a transverse section through the e:rcretory sac ot the nephrldilDll. X fvOO

- 43 -

The sac decreases in height as it passes back until at its posterior end its depth is about one-third ot that in the prostomium. The walls ot the sac are very much tolded in a mature worm; in young specimens the sac has the torm ot a simple tube. Numerous blood vessels run in the connective tissue surrounding the sac and extend up into the tolds in the wall.

·The sac is lined by an epithelium ot columnar cells ot rather unusual structure. At the distal end ot each cell there is a knob-shaped projection that shows no detinite oell wall. From. the end ot the cells a t:fJW long irregular cilia project into the lumen ot the sac. The nuclei ot the cells are large and darkly staining. Except at the distal tree ends the cells are packed with excretory granules. In un­stained sections these granules are greenish; in stained seotions they stain darkly with Heidenhain's and Delatiel.'s and ;yellowish brown with Mallory's.

The cytopla.- ot the cells does not show meta­chromatic staining with mucus stains.

In the peristemial segment each sae gives ott trom the inner dorsal surtaoe a narrQW tube running in the anterior septum ot the segment. These elucts are lined by a tlat non­ciliated epithelium. The duets 30in to torm a median tube which is much elongated in a dorso-ventral direotion in cross­.ection. The epithelium lining this median duct is similar to that ot the lateral ducts. On the dorsal surtace ot the brain there is a groove in which the duct runs. Anteriorly the duct runs in a ridge on the dorsal root ot the dorsal pit, opening by a pore at its anterior end. This ridge is strongl;y ciliated on its outer lurtace.

The structure and tunction ot the thoraoic nephridia ot Serpulids have been studied b;y Meyer (1887, 1888), Chigi (1890) and Soulier (1891). The development ot: the nephridia has been studied by Me;yer and Sergrove (1941). According to Meyer the tunnels and the ciliated tubes are derived tram the posterior septum ot the peristomial segment and are theretore, mesodermal~ The excretory sac is derived according to both accounts tram a pair ot e.todermal oells. Meyer tound that the medium duct was derived tram the rooting in ot a median ciliated groove and was theretore ot eotodermal origin; while Sergrove tound that it arose by outgrowths ot: the exoretory oells which pushed onto the dorsal surtace in the tirst septum) and then torwards between the cerebral ganglia and the over­lying eotoderm betore pertorating the latter. Thus, according to the above accounts ot their origin, these thoracic nephridia are classitied as mixonephridia (Goodrich

- 44 -

(i1 ) EXCRETION.

Tests were oarried out i~c~n attempt to establish the nature ot the exoretory granules w~qyin the oells ot the nephridial sao. Thiok,seotions ot the thoraoio area oontaining the nephridia were mounted on slides. plaoed in shallow petri. dishes with various solvents and examined at intervals under the miorosoope. The tollowing results were obtained:--

Aloohol Ether Chloro~orm Ammonia 2 % KOH

-insoluble insoluble insoluble insoluble soluble

5 % Rel Glaoial aoetio -

aoid Aoetohe Gl1'oerine

soluble slightly soluble insoluble insoluble

Thus the granules resist the aotion ot aloohol. ether, ohlorotorm, ammonia, aoetone and glyoerine and are soluble in potash and h7droohlorio aoid; these ohemioal charaoters oorrespond to guanine. Negative results were obtained using the murexide test tor urio aoid and urates.

The :t'unotion ot the oiliated tuDnel and tube"1s appaitently to oreate a ourrent ot ooelomio tluid into the eXoretory sao. Since the lumen ot the tube is small and almost blooked by cilia only tine particles oould travel down the tube. The large sao is the only portion ot the nephridium in which exoretion takes plaoe. Excretory products are probably extracted directly tram the blood by the oells ot the excretory sac, sinoe the blood supply to the sac is well developed and the bases ot the oells are in olose contaot with the blood vessels. The knob-shaped distal ends ot the oells have the appearanoe ot masses ot exoreted' material in the prooess ot elimination. In some seotions the lumen ot the sac contained large amounts ot very tine particles. The passage ot the exoreted material along the Sao and the empty­ing ot the sac must be due ohietly to the aotion ot the oiroular musoles ot the sao and the longitudinal musoles ot the body wall, since the lateral and median canals lack oilia.

- 45 -

15. BLOOD SYSTEM.

(i) PREVIOUS WORK.

The blood system of Serpulids has been studied by several authors including Clarapede (1873), Meyer (1888), ,Lee (1912) and Johansson (1927). Lee described the vascular system of Pamatoceros trigueter and Thomas (1940) redescribed it briefly. Tne vascular system of Serpulids resembles closely that of Sabellids and there have been several descriptions of the blood systems of various species of the latter group. The most reoent and most comprehensive account is that of EWer (1941).

( ii ) METHODS •

Paraffin sections prepared as desoribed above were used. Sections stained with Malloryts, Masson's trichrome sta,in and Mann's double stain were partioularly useful.

A modifioation of the method of staining blood by the benzidene reaction described' by Pickworth (1934) was used. Piol~orth used the freezing method for cutting sections which were then inoubated with the reagent~ used. In the present work it was found that, after fixation in four per cent solution of formaldehyde in sea-water, large worms oould be cut into several pieces, inoubated, embedded in paraffin and thick sections cut at 100 to 250 tf with good results.

Other worms were stained by a modification of the oommon chemical test for blood pigments as described by Faulkner (1930). Ewer (1941) used a s~ilar technique desoiibed by Solomimsky (1927) and states that the method has' the disadvantage of being useful only for small and living specimens. In the present investigation the following method was developed. A solution o~benzidine was obtained by sprinkling 8 little of the substance on sea-water. The water was filtered and speoimens were immersed in it for about half an hour. Hydrogen peroxide was then added drop by drop until small bubbles of gas appeared. When the blood vessels appeared dark blue the worms were fixed in 70 ro aloohol, dehydrated, oleared in benzol, and either mounted in Canada balsam as whole mounts, or embedded in paraffin and sectioned at 100 to 250 f.4. The blood vessels appeared as dark brown threads, the other tissues being transparent. The micro­photographs in Fi~ 3~1J9,40"ere taken from preparations prepared as above.

Small worms with as little pigment as possible were used to observe the directions of the blood flaw.

YV'\ e.G. \ 0. V"\ J. 0" so. \

l 0,;'\0 l t \Ac).\r\G\\ Y'Av..s<...\e.. J

se~Me",~'~ \ J.O'v':..>(,"\ \

\Ie \

"llV.oo~---\ a ""-0.. (?() J \ 0.\ ~~Jw. ve~~e\

~~-i!ii~sit2il~~7---t -I"(J-- I~, S - ~e~~(),\ \le~)~e\ ,

y-\V'\~ vesse\ ,

veV"\\-ro..\ \o,., ... \~,t'J..o.l'A(). \ ve'A\{(A \ "f' c, ".,co;, \

"e.V\ -\.-'0\ \ ~\(~/,d ":J~\e\J

ves'-::.f2. \

VV'\ v-. sc..\~

Fig. 36.

- .. ", ...,,\..,.,

Diagramatic view of an abdominal segment seen from a posterior aspect. ~e vessels in the muscles and glands of the right side are shown.

- 46 -

( iii) ANATOMY OF THE BLOOD-SYSTEN.

The circulation of the two regions of the body , thorax and abdomen, differs somewhat. That of the abdomen will be described first.

(a) ~ Abdomen.

The'general organisation of the blood system in the abdomen can be seen in Fig. 36. The vascular system consists of (a) the "longitudinal vessels - slit sinus'and ventral vessel -and (b) the oircular vessels in eac segment - ring vessels, segmental dorsal vessels, trans-septal vessels, parapoolal vessels, ventral Slana shie~essels.

The Gut Sinus:- (or peri-intestinal sinus). This sinus surrounds the gut from the anus to the anterior septum of the third segment. !n each segment it reoeives a pair of ring vessels ventro-laterally. In small transparent worms the blood oan be seen travelling forwards by the peristalsis of the sinus wall.

The Ventral Vessel:- The ventral vesseL runs backwards along the whole length of the animal from the posterior end of the second segment. It lies in the ventral mesentery between the ventral nerve oords and the giant fibres. The vessel is ciroular in cross seotion. A pair of ring vessels are given off from the ventral vessel immediately in front of each septum.

The Ring Vessels:- The paired ring vessels arise laterally and run along the ventral muscle block to the opening of the gonoduct, pass betwe~n the ooelamostone and the septum and then turn obliquely apwards and backwardS. It then bends sharply towards the ventral s~~ace, makes a oharacteristic S-shaped bend and opens into the gut sinus in a ventro-lateral position at the posterior end of the segment. At the first bend two vessels are given off, the trans-septal vessel: and a small vessel 'spreading out over the surface of the ventral musole block. A short distanoe before the seoond bend there arises the segmental dorsal vessel. The ventral portion of the ring vessel is covered with chloragogenous tissue. This is desoribed later.

The Trans-septa.l Vessels: - These arise from the ring vessels as desoribed above, and run baokwards thrcugh the septum along the surfaoe of the ventral musole block. As they pass through the septum they give off a small vessel

v \

\

;;;.F=.iSIOOlo.:,... ---I3~7:..;!. Phot omicrograph of t a bdOI!li 1 re io of orm stein d y tb enzedine m t od ,

fro the ve tlal surface .

- 47 -

the septal vessel which branches on the septum, the capillaries ending blindly. Behind the septum the trans-septal vessel forks to form the parapodial vess.el and the ventral gland­shield vessel.

The Parepodial Vessels:- These vessels run up-wards into the coelomic pouches of the parapodia. Blind­ending capillaries which project into the coelom are given off along the length of each vessel. A dorsal extension of the parapodial vessel spreads out under the epithelium dorsal to the parapodium.

The Ventral Gland Shield Vessel:- These arise from the trans-septal vessels as described above. Each vessel curves under the ventral muscle block where it divides ll.nto a number of branches which ramify in the ventral gland shield. The branches divide to form blind-ending capillaries.

The Se@!:ental Dorsal Vessels: - . The two segmental dorsal vessels of each segment arise from the ring vessels as described above. These vessels run up along the dorsal muscle blocks to the dorsal mesentery where they pass through to the dorsal surface terminating in blind-ending capillaries underneath the epidermis. Along the length of each vessel blind-ending capillaries arise and project into the coelom. About half-way along the length of each vessel is given off a vessel which runs dorsally along the posterior septum and through the dorsal muscle block to the dorso-lat_ral surface where it branches underneath the epidermis.

The Blind-ending Capillaries:- These arise from all the vessels except the ventral vessel, the ring vessels and the gut sinus. These capillaries never anastomose with each other.

The Terminal Segments:- The general plan as outlined above is found back to the last chaetigerous segment. In the terminal segments the ventral gland shields are particularly well-developed and are abundantly supplied with blind-ending capillaries.

(b) The Head and Thorax.

The general organization of the blood vessels in the head and thoracic segments is shown in Figs • .38 and 43. That of the thoraX will be described first.

( I) The Thorax.

In the thoracic region the basic plan as outlined

o V

~

I

Fig . 38. Diagramatic view o~ a thorac c segment seen fram the anterior aspect. The vessels in the uscles and gl nds of th Ie t s de ara sm.

- 48 -

for the abdomen is modified. This modification is due to the inversion of the position of the uncini and chaetae of the parapodia, the possession of the thoracic membrane and the very much enlarged nephridia.

The Gut Sinus, Oesophageal Plexus and Dorsal Vessel:- The gut sinus contInues to the anterIor end of the stomach, i.~., as far as the anterior septum of segment II. Beyond this point it is continued forward as a plexus of vessels anastomosing with each other, the oesophageal plexus. Dorsally a large vessel, the dorsal vessel, extends to the posterior end of the brain. The anterior part of this vessel has a thick wall of circular muscles.

The Ventral Vessel and Ring Vessels:- The vent.ral vessel runs as far as the anterIor end of segment II. The Ding vessels arise as in the abdamen; but are very much convoluted and are densly covered with chloragogen cells. Each ring vessel gives off a large segmental dorsal vessel and all the other branch vessels in the segment arise fram these vessels.

The se~ntal Dorsal Vessels:- Each vessel passes dorsally ~ough the musoles and connective tissue of the chaetal sac. Within the sac the vessel branches to form. a dorsal thoracic vessel, a thoracic membrane vessel and a parapodial vessel.

The Dorsal Thoracic Vessels:- These vessels run towards the mid-line underneath the epidermis, Corsally to the dorsal muscle blocks.

The Thoracic Membrane Vessels:- Each vessel passes up between the two layers of epithelium forming the membrane. They branch repeatedly terminating in blind­ending capillaries.

The Parapodial Vessels:- The parapodial glands . are particularlY well developed-in the thoracic region and

have a oopious blood supply. A short distance from its origin the parapodial vessel gives rise to a vessel which passes baok through the septum and supplies the dorsal part of the parapodium in the segment behind. Beyond the point of origin of this vessel the parapodial vessel bends and runs towards the ventral surface giving rise to large blind­ending capillaries ramifying in the par.podial gland and projecting into the coelomic pouch.

•

C I t ..... ,· \

o \ \ v \ at

Photomicrograph of a th ck sec 10 thro h the t or x tal ad b ~ the ben ed! 0 me o .

PhotomiCl'ogr ph of t e ventra surfa 0 the orax . stained y the benzedine met ode

- 49 -

The Ventral Gland Shield Vessels:- The para-podial yessel is continued into the ventral gland. shield as the ventral gland shield vessel. This vessel breaks up to form blind ending capillaries within the gland.

The Nethridial Blood SUPPl~- The nephridia are well supplied wi h blood vessels. anch vessels to the nephridia arise in each segment from the ~ing vessels, the segmental dorsal vessels and the parapodial vessels. Thomas (1941) found that the blood supply to the nephridia in Pamatooeros trigueter was very small and Ewer (1941) states that in Sabella there is no blood supply to the large thoraoio kidneys.

(2) The Head.

The Dorsal Vessel:- This vessel runs as far forward as the posterior end of the brain in the prostomium where it forks to form the transverse vessel.

The Transverse Vessel:- Above the ventral root of the oesophageal oonneotive on eaoh side,the transverse forks to form the basal branohial vessel which runs forwards, and the circum-oesophageal vessel which runs backwards and downwards behind the oonnective.

The ciroum-oesOPha~eal Vessels:- These vessels pass round the oesophagus an unite airthe posterior end of segment I to form the ventral vessel. From the ventral portion of eaoh vessel three main vessels are given off, a ventral gland shield vessel, a thoraoic membrane vessel and a collar vessel, supplying the collar region.

The Basal Branchial, Branchial and Plnnule Vessels:- The basal Dranohlal vessels pass between the dorsal and ventral roots of the oesophageal connectives and run forward to the base of each half of the branchial crown. Each vessel runs round the base of the orown giving off branchial vessels which end blindly at the tip of each filament. Along their length the branohial vessels give off short blind-ending vessels, the pinnule vessels, into the pinnules.

In her desoription of Pomatooeros tri~ueter, Thomas states that the ring vessels are joIned ~y a pair of lateral vessels extending the length of the worm. In Sabella also paired lateral vessels are present. In Pomatooeros coeruleus no evidence of lateral vessels has been seen on any of the prepared slides, whole mounts, or on the living worm.

tv'\1A~C.l.A \0-epAt-e.liuM.

<s~e\e\o.\ \ ().~ er

/ eV\c}~e\\() \

V'\ \At-\e \As.

6\ooJ

:rig.

b\ood.

~~Q.\Q.\()'\

ltAJe.v-

VV\\A~c\e .(: \ ~ yo-e..,

41.

Fis. 42,

Transverse section

.. ~ ; . .. ' .... , .. ' , . . '.

~ . .. . ~ ... ..

e"",<Ao·\-ke l \ \'\lfV\ through the gut sinus. '1..1160

Section through a ring vessel showing the cb1oragogen cells. 't..1·~~J

- 50 -

( iT) HISTOLOGY.

B. atteapt has been made at a detailed examination of the histolegy of the blood vessels. "a.~ (1949) has reviewed the histology of the blood system of the Polychaeta and discussed~the theories as to the origin of the vascular system within the group. The structure of the blood vessels of Serpulids appears to be uniform and that.of Pomatoceros coeruleus agrees with the published accounts for other members of the group_

The walls of the blood vessels conslstof three layers. On the inner side there is a flattene~ endothelium with long oval nuclei orientated with their long axes parall.l~ to the long axis of the vessel. Next there is a structureless skeletal layer and on the outer side a musculo­epithelial coat. This outer coat is ctmposed of muscle fibres arranged transversely to the long axis of the vessel. In cross-section the cell-bodies of the muscle fibres can be seen projecting trom the outer surface.

The outer wall of the gut sinus {Fig. 42) is composed of the same three layers with the outer muscular layer much enlargeO. On its inner side the blood sinus is bounded by an endothelium lying on another structureless layer which is the basement membrane of the gut cells. Across the lumen of the sinus are fine threads connecting the two skeletal layers. Similar structures have been describal by Faulkner (19:30) in Filosyana 1mpleJe., by .er (1941) in Sabeali pavonia and by Lee '1912} ~n a number of Serpulids.

ChlOra~Ogenous Tissue . T~e ring vessels are covered on the outside by a

mass of small cells (Fig. 43) •. 'l'hese cells are packed full of dark brown granules and the cytoplasm stains intensely with iron haematoxylln. ~ey are usually referred to as chlor-agogenous tissue and the cells are believed to contain iron .. and other breakdown products ot the blood pigment chlorocruoIin.

v 0 \

r

F • Disgra of t lood ves~e s f t anterior nd of the thora. he di action of t e lood-rIovT 1s _n . cate barrows.

- 51 -

(v) CIRCULATION. (Figs_ 43 & 44).

All the blood vessels of the body including the gut sinus and the blind-ending capillaries are r~thmioally contractile. The course of the circulation in the various vessels can be observed in a small wor.m under a binocular_

The gut sinus contracts rhythmically'trom behind forwards forcing the blood to the anterior end of the stomach, where it passes into the dorsal vessel and the oesophageal plexus. , From the dorsal vessel the blood passes into the transverse vessel, from which some of the blood will flow into the crown along the basal branchial vessels and some into the circum-oesophageal vessels_ Blood trom the basal ,branchial vessels passes into the branehial vessels in each filament and into the blind-ending pinnule vessels. Here the blood is retained fD~ a short time and then a contraction can be seen to start at the extreme tip of each branchial vessel passing rapidly to their base~ expelling the blood into the basal branchial vessels and thence into the trans­verse vessel. Re-entry of the blood into the dorsal vessel is probably prevented by the strong ciroular muscles that supround the vessel. Hence blood trom the crown passes into the circum-oesophageal vessels and down to the ventral vessel, along which the blood is propelled backwards_

Rhythmic trains of blood can be seen passing back­wards along the ventral vessel. As each train of blood comes opposite the ring vessels in each segment blood flows into them and thence into the branches leading from them, the parapodial, ventral gland shield and segmental dorsal vessels. When these vessels contract the blood passes back into the ring vessels and thence into the gut sinus and fOrIJITards.

The contractions of the various vessels are very regularly rhythmic; but their rates of contraction differ. The average periods, in seconds, of contractions in Pamatoceros coeruleus at ISO C. have been found to be as tollows: crown vessels S-2, gut-sinus 3-3, ventral vessel 4-6 and thoracic membrane capillaries 10-2. The periods of contraction are slower in large than in small individuals. The crown vessels remain empty for just over half the period of the cycle of vontraction and the greater trequency of the contractions of the gut sinus ensures that the oxygenated blood trom the crcwm is carried down the circum-oesophageal vessels to the vent~.l vessel, preventing the same portion of blood flowing back into the crown again. The blood in the gut sinus may be regarded as being deoxygenated while

- 52 -

tha.t in the ven.tral vessel is m.ixed, since some of the blood fro~. the dorsal vessel is carried directly to the ventral 'TmH"~el \I.:' thO\~t; flowing into the Cl"()wn. SOIrJ( cf the blood from the circum-oesophageal vessels passes into the collar where further aeration will take place.

The capillary vesse.l of each segment all contract at the same time, the contraction in one segment being one or more seconds behind those in the segment immediately anterior to it. All the vess~ in the filaments in each hal" of the crovm contract synchronously; but the contractions in the two halves of the crown may not be simUltaneous. Experiments involving the amputation of the c~ were interesting. If the terminal halves of the filaments are amputated the rhythm of the truncated vessels is unchanged. If one half of the crown is amputated at the base contractions continue in the isolated portion for a period of up to 36 hours. The immediate result is an acceleration of the rhytb;. The vesse~ in an isolated portion of the collar will also con­tinue rhythmic contractions for a considerable period.

(vi) THE BLIND-ENDING CAPILIARIES.

Bling-end.ing capillaries are one of the peculiarities of the blood-system of the Sabelliformia. Similar vesse~~ occur in other Polychaetesj bu~ they are not generallyaistributed, being confined mainly to the ves9~ supplying the segmental organs and the gonads. Bl1n~-.nding capillary vessels projecting into the coelom are characteristic of Sabellids (Fox, 1933, 1938) and have also been found in a number of Serpulids. Fox (1938) has put forward two suggestions about the function of the coelomic capillaries in Sabella. Pointing out the absence of any capillaries in the muscles he suggests that the oxygen supply to the muscles must come by way of the coelomic fluid, in which a high oxygen concentration would be maintained by diffusion of oxygen from the coelomic capillaries. Re also suggests that in the breeding season the capillaries may carry oxygen to the genital products which lie free in the coelomic fluid.

In Pomatooeros coeruleus no blood vessels have been seen among the main blocks of longitudinal muscles. Blind­ending coelomic capillaries project into the coelom of the abdomen from the segmental dorsal vessell and the parapodial vessels. Blood vessels also run in the septa separating the segments and under the peritoneum covering the ventral muscle blocks. In the thoracic region the ring vessels are very much convoluted, occupying most of the thoracic coelom.

- 53 -

Numerous blood vessels also ~un underneath the epithelium oovering the muscle blocks. The oxygen supply to the muscl~ therefore must be derived from the surrounding blood vessels and from the coelomic fluid. Fox (1926) suggests that the relatively high unloeding tension of the respiratory pigment chlorocruorin would assist the oxygen supply to the musoles through the intermediary of the coelomic fluid. The suggestion that the coelomic capillaries may also be required to supply oxygen to the genital products in the breeding season may also be valid for Pomatoceros since the coelomic capillaries are only to be found in the abdominal segments which alone bear gonads.

(vii) REVERSIBLE STOPPAGE.

If an individual Pomatoceros is removed from its tube and put into a small length of glass tubing, corked at the posterior end of the worm, the contractions of the blood vessels of the crown, the thoracic membrane and the parapodia can be observed through the glass under a binocular. The rhythmic contractions 'occur normally for about 30 minutes, after which they begin to slow down, finally ceasing after about 45 minutes. If the worm is taken out of the tube the contractions or the vessels begin once again. Thus it appears that when the worms retract into their tubes for any period exceeding 45 minutes their blood circulation stops. In a series of experiments described later it was found that the worms could remain in their tubes for a period of up to 7 days, wihhout ill-effect. During this period then, the circulation of the blood will be stopped.

Fox (1933, 1938) carried out extensive experimen.ts on this problem of reversible stoppage in Sabella and Spiro­~apsis and put forward the hypothesis that the accumulation o car~onic acid around the body and in the blood causes the contractions to cease. The phenomenon of the reversible inhibition of blood circulation is apparently widespread in the animal kingdom, being reported by Fox for Sabellidsj the dorsal blood vessel of Nereis; the heart of Daphnia, Artemia, Chloeon nymphs, Phallusia (an ascid.ian); chick embryos; and the contractile vesicles of Limax embryos. Experiments with Pomatoceros coeruleus indicate that the phenomenon is somewhat similar to that reported by Fox for Spirograpsis. If the worms were put into carbon-dioxide saturated sea-water the contractions of the blood vessels stopped almost immediately. If they were replaced in pure sea-water the contractions soon recommenced. It was also found that the contractions were inhibited by oxygen-free sea-water prepared by boiling and cooling under paraffin;

Diagramatic view of the worm within the tube showing the direction of the currents within the tube.

- 54 -

but that the inhibition was slow. Fox found th~t Spirograpsis showed no response to oxygen lack when kept in oxygen-free sea-water for one hour. When the worms are retracted into their tubes the operculum forms a tight plug preventing the entry or exit of water. Thus the only available oxygen would be that in the ~lood and in the small amount of water surrounding the worm. The inhibition of the contractions of the blood vessels would reduce the rate of metabolism.

(viii) RESPIRATION.

The nature of the blood pigment, chlorocruorin which is found only in the blood of Sabellid1Serpulid and Chlorhaemid worms has been extensively studied by Fox (1926, 1932, 1934). It is closely allied to haemoglobin; but differs from it in having a different ~ and a different l!otein. While the ratio of oxygen to iron is the same in oxychlorocruorin as in oxyhaemoglobin, chlorocruorin has a higher proportion of iron to other elements in its molecule than has haemoglobin. Chlorocruorin may thus be reg\}.arded as a better transpor'tllr of oxygen. The pigment chlorocruorin is red in concentrated solution and green in dilute solution. The green colour of the blood can be seen in the ve'saels ot"thB- crown 'and in the collar and the thoracic membrane. That::J.n the gut sinus and in the larger vessels appears a dark red.

Respiratory exchange in the Sabelliformia takes place mainly through the branchial crown; but also through the general body surface. Zoond (1931) and Fox (~93S) have shown that the crown in Sabellids accounts for 63 ~o of the total oxygen intake. The distribution of the epidermal cilla of the body has been dealt with and these cilia are responsible for the m.a:tntenance of the circulation of the water within tle tube. Since the posterior end of the tube is blocked by debris, over grown by other tubes and sealed off by the partitions mentioned above, it is impossible for water to enter the ree.r of the tube. The cilia of the ventra) groove create an outward current which passes round each sidenof the posterior end of the thoraX on to the dorsal surface of the thorax, where an exhalent current passes to the mouth of the tube (Fig. 45). Within the tube the two halves of the thoracic membrane meet in the mid dorsal line forming a semioylindrical canal. The inner surface of the membrane is covered with cilia which beat in an antero-posterior direction

i causing a compensating current to that produced

by the ci ia on the dorsal surface of the thorex. The

- 55 -

course of the above currents was observed by placing the worms in glass-tubes and adding carmine to the water. It was also observed that the abdomen contracted and expanded rhythmically, the movements assisting in the circulation of water round the posterior end of the worm.

According to Meyer (1929) and Sergrove (1938) the primitive Annelid possessed the following typical features: coelomic ciliation and coelomic circulation, vascular system incomplete or wanting, respiratory pigments located in the epidermis in association with sense cells and the central nervous system, and well-developed epidermal and intestinal cilia. Pomatoeeros coeruleus possesses a fairly well­dev~loped circulating system and blood pigment. Consequently the respiratory functions of the coelom has disappeared and coelomic cilia are absent. In Errant Polychaetes the association of respiratory pigment with the blood-vascular system leads to the disappearance of epidermal cilia. They are. however, retained in tubicolous forms where they have also assumed the secondary function of getting rid of waste mat·ter from the inside of the tube. Stephenson (1913) con­sidered that many aquatic annelids. including Pomatoceros trigueter used the posterior part of the alimentary canal as a respiratory surface. water being drawn in at the anus by the action of the intestinal cilia in conjunction with t"he postero-anterior peristaltic contractions of the gut sinus. No such current has been observed in Pomatooeros coeruleus in v<Thich the intestinal cilia beat in an antero­posterIor direction.

\

F

o

Phot c ogre ph of a tr nsverse ~e'ction hrough th rain. qO

~ \ " Phvt microgra h of 8 sec ion through t e

reristamium, passing t o~g h sub­oesophageal ge glia.

- 56 -

16. THE NERVOUS SYSTJI.

( i ) ANATCI4Y AND HISTOLOGY.

Qua~tretages (1850) gave a briet description of the nervous system ot Pamatoceros trigueter and Serpula contortu­~licata. Later, more detailed accounts of the nervous

. sp:stem ot Serpulids were given by Meyer (1888) for Eupomatus lunuliterus, by Treadwell (1891) tor Serpu~ dianthus, tor Serpulavermicularis by Johansson (1927) and tor Pamatoceros tr!gueter by Thomas (1940). The nervous system ot Pamatocero~ coerul •• s agrees with the above accounts in its maIn features.

The nervous system consists ot a brain situated in the prostamium connected by a pair ot circum-vesophageal connectives to the sub-oesophageal ganglia in the ventral part of the peristomium. From these ganglia a pair of widely separated nerve cords, connected by commissures in each segment, run back, torming a typical ladder-like arrangement.

The brain (Fig. 46 ) lies in the prostam1um above theO~hagus. It is a large bilobed structure, grooved on the Aorsal surtace where the median excretory canal passes over the brain. The main mass ot the brain is composed ot transverse fibres, with the nerve cells confined to the periphery. The arrangement of these cells and the fibres indicates that there are two pair ot ganglia or nerve masses in the brain. The brain ot Po1ychaetes usually shows three pairs of ganglia, the first innervating the palps, the second the antennae, the third the nuchal organ. Since the latter structure appears to be absent in Serpulids and the posterior ganglion is absent in Pamatoceros coeruleus the brain contains only two pairs ot ganglia. The only Serpulid in which. pair ot posterior ganglia have been reported is· Filosrana imple:ra (Faulkner 1930).

At the dorsal anterior end ot the brain there is an anterior lobe on each side, giving rise to a pair of stout nerves, the internal branchial nerve trunks. Each of these nerve trunks bears a ganglionic swelling a short distance trom the brain. Beyond this the nerve runs in the connective tissue on the inner side ot the coelomic space, containing the basal branchial blood vessels. Each nerve trunk runs round the base ot the crown giving ott a branch to each filament, the internal branchial aerve, lying on the basement membrane underneath the tllamentar groove. As this nerve passes up the tilaments it gives oft paired branches to the pinnules. Just before the origin at the first internal branchial nerve a nerve supplying the palp and the dorsal and ventral lips is

- 57 -

given off. The opercu1um is supplied by a nerve arising from the dorsal surface of the brain (Fig. 46), just'posterior to the origin of the left internal branchial nerve trunk. From the posterior end of the brain a median dorsal nerTe runs back above the dorsal blood vessel on to the gut sinus.

, The circum-oesOphateal connectives arise laterally from the brain by stout dorsa and ventral roots. These roots enclose between them the coelomic canal in whioh runs the basal branchial blood vessel. The dorsal and ventral roots unite and immediately swell to form the sub-oesoPhaseal ganglion lying in the peristomial segment. Tne-two sub­oesophageal ganglia are widely separated and are connected by a stout transverse commissure.

Just after the dorsal roots leave the brain they give rise to the external branchial nerve trunks which run in the connective tissue on the outer side of the coelomic space in the base of the crown. Each trunk divides to send branches into the filaments, each branch dividing to form a pair of external branchial nerves, running between the bases of the epIthelial cells on the outer corners of the filaments. Thus the filaments have a double nerve supply and this appears to be a characteristic feature of Serpulids. Another pair of stout nerves arise from the outer ends of the dorsal roots. These are the Oblique branchial nerves running to the oblique branchial muscles.

Arising fram the sub-oesophageal ganglia there are three main pairs of nerves, as well as several smaller ones. The most dorsal of these, arising fram the junction of the connectives with the ganglion is the lateral sense organ nerve (Fig. 47) running out to supp.1y the lateral sense organ. From the outer side of the ganglia a pair of stout collar nerves are given off, running to the collar. Another pair of nerves arising ventrally from the ganglia supply the ventral longitudinal muscles of the thorax and the ventral gland shield area •.

From the sub-oesophageal ganglia the paired ventral nerve cords run back. In the thoracic region they are wlaelj' separated, lying in the vonnective tissue between the ventral longitudinal muscles of the thorax and the ciliated duct of the nephridium. Towards the rear end of the thorax they pass over dorsally to the longitudinal muscles and in the abdominal region lie between the ventral blood vessel and the inner ends of the ventral longitudinal muscles. Posterior to each septum the nerve cords swell to form ganglia which alone contain

o c \ \

F 8 , 48 ,

v s \

Photamicrograp 0 a section through the lateral sense orga , ~

- 58 -

nerve cells. From each ganglion several pairs of segmental nerves are given off. These run under the epithelium in the connective tissue.

Giant nerve fibres are very well developed in the nerve cords. There is one large fibre in each cord, origin­ating in the sub-oesophaegealge.nglion and increasing in size as it passes back, until in the abdominal region it occupies more than half of the diameter of the cord. Giant nerve fibres reach their greatest development in the Sabelliformia and this is' correlated with their tubicolous habits. With the adoption of a sedentary habit the need for the complex forms of behavioUl! characteristic of free-living forms was no l.nger present, and it enabled one part of the nervous system to beoome highly specialised. Nicol (1948) has studied the structure and physiology of the giant fibres of AmRhitrite. He found that the nerve impulse travelled at the rate of 11 metres per seoond in the giant fibres asoo)lpared with 54·5 oentimetres in an ordinary fibre. This increased rate of transmission enables.the worm to contraot as a unit in quick withdrawal fram noxious stimuli.

(ii) SENSE ORGANS.

Several organs in Serpulids are suspeoted to have a sensery function; .but as yet nothing is known regarding the sttaull to which they are sensitive or of their mode of working. These organs are the dorsal pit, the lappets at the junotion of the lateral and ventral collar ~Olds and the paired lateral sense organs situated in the collar.

The paired lateral sense organs (Fig.48 ) consist of a number of coiled tubules lying between the epithelium and the sub-oesophageal ganglion and extending into the base of the collar fold. They open externally on the ventral surface of the peristomial segment. The tubules are lined with a cubical epithelium which is ciliated in parts. The ciliated regions are lighter staining than the non-ciliated. Each organ is supplied by a nerve from the sub-oesophageal ganglion. Their function is unknown and they do not appear to be homologous with any known senSe organs in Polychaetes.

P.otomicrogreph of a sectio tough t e abdomen of H me urp feme 1 , ss

ough the gonoduct . ~

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17. REPRODUCTIVE SYSTEM.

The sexes are separate and males and females can be distinguished externally at maturity by the colour of the abdomen, yellowish in-the male and pinkish in the female. The gonads are attached to the septum at the anterior end ~ each abdominal segment. The male germ cells are shed into the coelom as spermatagonia or primary spermatocytes. Wit hin the coelom cells in various stages of sperm formation can be seen. The 'female germ cells when shed into the coelom are in the primary oocyte stage and in the mature female are closely packed, filling the whole of the coelomic cavity surroundfug the intestine and the coelomic pouches of the parapodia ~g.49).

There are a pair of gonoducts in each abdominal segment. According to Meyer (1887) they represent a combined nephridium and coelonioduct and are therefore nephromixia. Each gonoduct has a large ciliated funnel, the coelomostome, opening into the coelom between the dorsal and ventral muscle blocks. This coelomostome opens into a ciliated duct (F~~ ) in the segment behind. This duct runs down under the ventra! muscle block and opens to the exterior on the ventral sur:tB c e to one side of the ventral groove. When shed the germ cells travel along the ventral groove to the exterior. The ducts act as gonoducts only having lost their excretory function and according to Goodrich (1948) wou~d be classified as mixonephridia. The duct is ciliated throughout its length, the cilia being particularly long near the opening and much more dense on the dorsal surface of the duct.

The egg and early cleavage stages.

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18. DEVELOPMENT.

. The development of Poly-chaetes has attracted a

great·· deal of attention from workers in various parts of the lII'Drid; but so tar practically no work has been done on .•. ew Zealand species. Sergrove . (1941) has described the detel.op- . ment of the European species, Pamatoceros trigueter L. l~ detail. My own observations show that the development ot· the New Zealand species closely parallels that of the European species •. Accordingly nb detailed work has been· attempted.

( i ) METHODS ".

Supplies of worms were obtained periodically fran the area at Taylor's Mistake where the ecological survey was made. They were removed from their tubes by breaking off· the rear end and pushing on the operculum with a seeker. Mature indivtduals are ea~1~y distinguishable, the abdomen of the female being a bright pink and that of the male yellowish-white in colour. As found by Sergrove (194l) and Cl;'agg (1939) the two sexes are in unequal numbers. Cragg examined over 3,000 species of Fomatoceros trigueter and found a sex-ratio of about five females to one male. Several counts of the sex-ratio of the local species were made, the average ratio being about four females to one male. No size difference between the sexes was observed, mature individuals of both sexes ranging from cm. to cm. in length.

When removed from their tubes the worms immediately began to-discharge their germ-cells through the paired abQom.i~l apertures. They streamed up the ventral grove following the course of the tube currents mentioned above. The sexes were separated, rinsed and placed in small glass bawls.where they discharged their sexual pr9ductS. Sterilized apparatus and filtered sea-water was used in making fertilizations. However, it was found that effect.ive fertilizations ~ould be made with­out taking the above precautions. Practically complete lib er­ation of eggs and sperms occurred within ten minutes. The worms were then removed and a few c.c. of sperm infusion was added to the eggs. The contents were then stirred and left for about an hour, the eggs settling to the bottom. Superfluous sperm was poured off and the eggs washed with several changes of sea-water. The eggs were then allowed to hatch and the free swimming larvae were transferred to large bowls. Air was bubbled into some of these; others simply being covered and left.

Unfortunately it has not been possible to rear the larvae beyond the fully developed trochosphere stage. One

l i--.OJA I f:~. S4.

FiS· 21• The blastula.

FiS· 22• The gastrula.

Fig. 23. 8 hour larva.

Fig I 2S:· 16 hour larva.

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batch of larvae were kept for three weeks without showing indications of segmentation. Fertilizations were made on numerous occasions throughout the year. The apparatus was sterilized and experiments were made with filtered and steril­ized sea-water. Cultures of various algae and diatoms were prepared by the method described by Allen (1910) in attempts to feed the larvae. In many cases the cult~es became infected with a small ciliate which quickly destroyed the larvae.

Natural spawning~' , Worms were kept in an aquarium for over a year and

at no time was natural spawning observed. Neither Sergrove (1941) or Gragg (1939) observed natural spawning in Pamatoceros trigueter although this has been seen at Naples by Fuchs (1911). However, on several occasions when tubes were opened they were found to be full of disoharged eggs or sperms. This discharge may have been stimulated by the handling of the tube. Mature individuals were found throughout the year, although they were rare from June to September. It was found that fertility was increased by keeping the worms in an aquarium. After several months in the aquarium the number of eggsdisch8rged was: several times that of freshly obtained worms. 'The eggs were apparently stored because the natural st~us for spawning was absent. Natural spawning is probably related to the,tidal ~bm.

(ii) EGG AND C1:& VAGE STAGES. ,l'

,When snea 'tlle eggs are primary oocyties ~ brigh:t pink in colour with a large clear germinal vesicle (Fig. 50). A large nuvleQlus is present in each nucleus. The egg is surrounded by a vitelline membrane about 2~ thiek. When liberated the eggs are indented on one side, probably due to their heing tightly packed in the body cavity. These indented eggs can be seen in sections through the abdomen of mature females (Fig. 49). The mean diameter of such eggs is approx­imately 60 fA. After liberation a varying percentage of the eggs mature. Maturation is indicated by the breakdown of the germinal vesicle and the assumption of an approximately spherical shape.

Segmentation begins one to two hours after the sperm has been added. The first cleavage divides the egg into two eXactly equal halves and the second results in four equal cells. With the third cleavage four somewhat smaller micrameres are separated by a dexitropic division from the lower macromeres. Subsequent cleavages follow the usual spiral pattern and result in the formation of a typical tlastula after four hours.

Gastrulation commences about five hours after the first cleavage. It is of the modified embolic type as described by Shearer (1911) for Hyroides uncinatus (Eupamatus). There

,-

Fig. 55.

Fig. 56.

I '~'. \.

24 hour larva.

2 day trochosphere.

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is a considerable flattening of the ventral surface followed by invagination to produce a gastrula with a slit-like blastopore. At first there is complete obliteration of the blastocoel; but later the larva increases in size and the ectoderm and endoderm separate to form the coelomic cavity. An apical tuft and a

. prototroch of a single row of cilia are found after eight hours when the spherical larva commences to swim. By 24 hours the anus has appeared and the archenteron has become divided into oesophagus, stomach and gut. At this 'stage the anal vesicle begins to appear as a vacuole in one of the ectoderm cells near the anus. The egg membrane is retained' throughout and becomes the cuticle of the trochosphere.

(iii) THE TROCHOSPHERE.

A typical trochoshpere larva with prototroch and neurotroch is formed in two days. It is of a length of approximately 100,..,. For about two da.ys there is very 11 ttle increase in size. During this time a second row of cilia appear in the prototroch and the head vesicle makes its appear­ance. At this stage (Fig. 56) the larval mesenchyme cells (ectomesoblast) are visible as a group of cells clustered IOund the stomodaeum. At the same time the head-kidney makes its appearance. Near the end of the head-kidney, close to tm anus, two large conspiouous cells are present. These are the coelamoblast cells.

The growth of the trochosphere is fairly rapid and the stage shown in Fig. 57 is reached after a week. The fo llow­ing description is of·this older larva.

The trochosphere has a length, excluding cilia ~ of 115 fA and a maximum width of 90 f4 aoross the region of til e prototroch. It is approximately pearshaped with ahemi-." spherical episphere and a cone-shaped 'llY'pos'pl1ere. There'18 an apical tuft of sensory cilia with a length of 60 f4: and a an ailer tuft of cilia at the tip of thehyPosPhere. The prototroch consists of two rows of locomotor cilia, an outer ring,of stout cilia about 30 ~ in length and an i,nnerone of slenderer cil ia about half the length. Another ring of locomotor cilia., th e meta.troch, is present just behind the mouth. These cilia are short and stout and beat posteriorly. Between the prototlDch and metatroch there is a broad band of feeding cilia. In the living larva these cilia can be seen on both sides, beating rapidly towards the mouth. The locomotor cilia throw fooo. particles on to these feeding cilia whence they are conveyed to the mouth. On the ventral surface there is a narrow band of cilia, the neurotroch, running from the mouth to the posterior end. ,The various cilia can be seen passing through the

. . I

\ \3- \ t

~e(:>6t~ c ,LCA ---­ _ _____ rA 0. \,f, \l

l'Y\e\~\("oc.~ -~-.. - VV'\e~''''''''( kj~'_'

,II/~--rtffll-------.-~E'a_(.\ hI J."'t?~ --." --- .. -- -

Fig. 57. The fully formed trochosphere at 7 days

- 63 -

persistant egg membrane.

The blastocoelic, body-cavity is very large and ~ eltmentary canal can easily be seen through the transpareft ectoderm. The mouth forms a conspicuous aperture in the mid­ventral line in the track of feeding cilia. It leads into the stomodaeum which runs forward as the oesophagus and opens :i:nto a large stomach. At the dorsal end the stomach opens by a narrow aperture into the intestine, which runs backwards ending in a short proctodaeum opening on to the dorsal surface. A tuft of s·tift cilia project from the anus. The alimentary canal is ciliated throughout its length.

, The ectojerm is composed of transparent flattened cells, thickened in the region of the prototroch and the apical organ. At the posterior end there is a large anal vesicle which, as mentioned previously, is developed from a single ectoderm cell. It i~ the development ofthia vesicle that causes the displacement of the anus onto the dorsal surface. A head vesicle, whicll appears later t1;lan the anal, is also present, lying anteriorly tp the apical "organ.. 'l'hese vesicles are a prominent feature of many Polychaete lar'vae especially of Sabellids and Serpulids. As yet the function of these vesicles is unknown. On the right side of the episphere, about half-way between the apical organ and the prototroch, there is a black pigment spot in the ectoderm. This is the right eye-spot which develops 'before the left. This feature is also exhibited by the trochosphere of Eupomatus and Pomatoceros trigueter.

Larval mesenchyme cells can be seen forming a group ot cells on the dorso-lateral walls' of the oesophagus and a small cluster under the apical organ. The trochosphere possesses a typical pair of head~kidneys. These are a pair of thin-walled tubes forked at the anterior end where they are attached to the oesophagus. At the posterior end they finish near the anterior end of the proctodaeum. The openings have not been observed. A long cilium arising from the anterior end can be seen flickering within the cavity. The structure of this organ is similar to that of PSymobranchus (Meyer 1888), Eupomatus (Shearer 1911), and Pomatoceros trigueter (Sergrave 1941). Tht~f coelomoblast cells have at this stage formed two groups of cells in the angle between the head-kidney and too anal vesicle.

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(iv) DISCUSSION.

It is now clear from the researches of various workers especially those of Wilson (1936 etc.) that a trocho­stl~ere, such as that desribed above, is specialized rather than primitive. As Shearer (1911) pointed out it was unfortunate that the. trochosphere described by Hatschek in Eupomatus came to be regarded as the typical Annelid trochosphere. Actually it is restricted to certain Serpulids and Polygordius, although text-books still desribe it as the 'typical' trochosphere. Wilson regards a larva such as occurs in Sabella as a more characteristic troahosphere of Polychaetes as a whole.

According to Sergrove (1941) true trocho8phere larvae develop from comparatively small eggs, poorly supplied with yolk, whilst on the other hand large yolky eggs give rise to larvae in which the 'typical' trochosphere features are more or less supressed. The larva of Pomatoceros coeruleus falls into the former category. There is very little yolk in the egg and development is extremely rapid. The larvae connnenee swimming a few hours after fertilization and locomotor cilia and feeding structures are quickly formed. The trochospmr e is essentially a feeding stage, hence its protracted pelaglc existance.

A t onsvelse s ion throu h the tb018Cic eobrane th thr e comensa ciliet 9 , lchodlna sp . 7&0

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19. COMMENSAIB & PARASITES.

The majority of worms w~amined were infected with large numbers of a ureoeolarid peritrich ciliate, Trichodina sp. The number of ciliates infecting a single worm has been estimated as being up to 250. They are found clustered round the ventral groove on the abdomen, on the dorsal surfa~ of the thorax and on the thoracic membrane and collar. Their distribution would indicate that they derive their food trom the currents created by the worm within the tube.

The shape of the ciliate (Fig. 58 ) is extremely variable, varying from hemi-spherioal to almost barrel­shaped. Two rings of cilia, an anterior oral and a posterior aboral ring can be distinguished and internal to the latter lies the typical skeletal complex. Within the oytoplasm a large contractile vacuele and food vaouoles can be seen. The macronucleus is large and horse-shoe shaped. They are normally attached firmly to the o*tiole by the aboral adhesive disc and when they move around on the surface they follow a spiral path. No pathenogenio effect has been observed and the ciliate can be regarded as a commensal not a parasite.

A large percentage of the worms examined were infected by a gregarine parasite. Sections show large numbers of these parasites in the stomach region and in the intestine.

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20. EXPERIMENTAL· ECOLOGY.

( i) TEMPERl"TURE TOLERANCE.

Field observations were made during 1949 at Taylorts Mistake in order to determine the aotual temperature range that was tolerated under natural oonditions. A serles o~ rook pools, ranging trom E.R.W.S. tide-~evel to below mid­tide level, were ohosen and the t~peratures were reoorded at frequent intervals. The hlghest pool showed the greatest range 22·70 C., the maximum t$mperature reoorded being 27·6°C. in January and the lowest 4-90 0 on June ,the

Opportunity was taken of a very hot period during March to records the temperature on the rock surface and in shallow pools in rook crevices. Observations were made between 1.30 and 2 p.m. on Maroh <::9,..4 t\,..". The air temperature at the time was 26.40 0. and the marl.mum temperature recorded on the rock surtaoe, among the tubes o~ Pamatoceros coeruleus, was 280 c. A selection of the results obtained are tabulated below.

Air temp. Sea temp. Maximum. temp. on the rook

Description of rock pool.

Sallow depression; 2 ins. deep at M.R.W.S.

Pool; 2 tt. by 1 ft. and 7 ins. deep at M.R.W.N.

Pool in orevice; 2 ins, de,p at M.T.L.

Shallow pool at M.H.W.N. containing !!J:!!. Lactuca

Pool; 18 ins. deep at M.T.L. contain-

Surface TemE·

3,.30

24·,

30.90 C.

330 C.

ing Rormosira. 27.60 o. Large pool 6 ft. across and 2 tt. 6 ins.

deep at E.L.W.N. con­taining dense growth o~ brown sea-weeds. 23.40 C.

Bottom Temp.

21.00 o. All the above pools contained specimens ot

Pamatoceros coeruleus whiCh are subject to relatively high temperatures when the tide is out, especially in the very

- 67 -.

shallow rock pools. At night in the summer~sea temperatures of about 150 C. were recorded. The diurnal temperature range that Pamatoceros coeruleus may be subjected to is there­fore about 20.30 C. In the deeper pools there is a signif­icant difference between the surface and the bottom temper­atures.

(ii) SALINITY TOLERANCE.

When the above temperature recordings were made, samples of water from the pools were collected for salinity determination which were made by titrating 10 c.o. of the sample with the solution containins 27~25 gm. of silver nitrate per litre. The salinity (S 'fool was calculated by applying the correotion given in the table on page 20 of Harvey's book (1927). The highest salinity recorded was 53·4 °/00 and the lowest 25-6 ~/oo. These results indicated that Pomatoceros coeru1eus is able to withstand a considerab~ variation in salinIty witS no apparent ill-erfects. Pomatoc~os

'coeruleus is commonly found in estuarine conditions and is quite cammon in the Heathcote Estuary. It was decided, there­fore, to carry out a series of expertments to determine the aotual salinity range that Pamatoceros coeruleus is able to tolerate.

(a) Deoreased Salinity.

For the ~urpose of this experiment sea-water having a salinity of 33 0/00 was taken as normal. From this normal sea-water a series ot solutions, down to 0·1 N, were made by adding the requisite amount ot distilled water. 100 c.o. of eaoh solution was placed in a covered glass dish and three worms were added to each. The level ot the water was marked and distilled water added if evaporation had taken place. Two series ot experiments were made, one with the worms in their tubes and one with tu~ss worms. The results of the experiments are given in the following table and in the graph in Fig.59.

" 10

.)

Fig.

• • I •

f I I I I I I I I

I I I~

I I ,

01

, , '"

1 •

I . , . I . I . I . I • I

I · I .' , I

" ;P I / I ·

I 0 ,/0 I / I 0./'

I ./ I 0/

/ . /./'

0--0 w,\-h 1-1Abe.:, 0·--0 w"\~~v\.\-" h ... b

~A(~ .,-'!?

~.

D-Itl ()v..tJ .-~ o-4W o·itJ O·LW 0-1ti o·,W O'9W ,-ow.

59.

S\-("ew"\~ th 0+ ~e.~ l.Jo.tec.

Graph showing survival time in sea-waDer o~ decreasing salinity.

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TABLE. I SURVIVAL TIME OF POMATd'CEROS COERULEUS IN a:u.­WATER OF DECREASED SALINITY.

Survival time. Strensth of solution Wi th tube Tubeless

Distilled Water 1 hr. A few mins. 0·1 N 12 hr. 12 hr. 0·2 If 12 hr. 12 hr. 0.3 N 3 days 2d8JS 0·4 If 8 days 3 days 0.5 If 10 days 4 days 0·6 N More than 15 days 4 days 0·7 N " " " tt 6 days o·S N " '" tt " More than 15 dE\'fs 0.9 N " " " '" " " If " 1.0 N " " " " " tt tt "

From the above results it can be seen that the critical salinity for Pamatoceros coeruleus under experimen~al conditions is between 16·5 u/oo ana 19·8 0/00 or ·5 If and 6 N. In sea-water of this strength and above the species Ii •• quite normally and would be able to survive salinities down to 9-9 0/00 for a short period. The fall in salinity under experimenatal conditions was a rapid one, far more sudden than could possibly occur in high rock pools due to dilution by rain. With a more gradual change the species might even be able to survive a much lower salinity.

(b) Inoreased salinity.

In order to test the effeot of increased salinity 500 o.c. of sea-water were placed in a glass trough, the depth of the solution being one inch. A similar trough, also containing 500 c.c. of sea-water, was placed alongside. Twelve specimens of Pomatoceros ooeruleus in their tubes were placed in one di8h whioh was uncovered and allowed to evaporate slowly. The salinity was determined at the beginning of the

. experiment and onoe daily,URtl1 all the worms were dead_ 2 c.c. were removed eaoh time for testing and replaoed by 2 0.0. tram the other dish whioh was kept under the same oonditions •

. The results of the experiment are given in Table II!,

- 69 -

TABLE_ m .. RESISTANCE OF POMATOCEROS COERULEUS TO GRADUALLY !NCREAS!NG SALINIT!.

~- Salini ty 0/00 Remarks

Nov_ 3 34 No reaotion. 4 36-1 " " 5, 39-6 " " 6 41-7 " " 7 43-6 " " 8 45-8 " " 9 47-9 " " 10 50-4 It " 11 52-7 " "

12 ,54-9 " " 13 57-0 " " 14 62·4 Sluggish in retraoting. 15 65-5 " " " 16 69-1 " " " 17 73-8 vert slugAish " 18 81-4 " " 19 83-7 Would not retract 20 85-8 " " " 21 87-7 " " " 22 99-8 Death

The worms seemed unatEected by the inoreasing salinity until it reaohed 62-4 Yoo. Atter this point they became very sluggish in retraoting into their tubes and ~en a salinity of 83-7 0/00 was reached the; thoraoio region protruded fram the tube and they tailed to retraot upon stimulation.

The majority ot marine invertebrates oannot survive aore than a very small change in the salinity ot the water 1b wbloh they live_ Reid (1929) tound that the salinity range of Arenieola marina lies between 35 and 25 0/00 _ The salinity range ot ~amatooeros coeruleus lies between 17-6 and 62-4 0/00 t showing that the species oan tolerate a wide Yariation in salinity, enabling it to live under estuarine conditions.

( iii) QU'l'I0If TO OTHER ADVERSE CONDITIONS.

(a) Exposure_

During the period ot low neap tides, worms inhabit­ing high rock pools are subjeot to exposure due to evaporation_

F 60

.:..F=1~...:..6~

Photogrep of a rock a "P ni ula rer~ lit

T ylor ' s i tare, Banks Pamatocero ~ es .

he same ro k S ove ith t e Po toceros enorustation covered it a d .

- 70 -

To test the etf'ect of' exposure a number of' worms were reDD ved tr~m the sea-water aquarium in which they were living and exposed to the air. Several were returned to the aquarium daily and their reaction noted. It was tound that they would show complete recovery when exposed f'or a period ot up to six days. If' they were exposed f'or a longer period death ensued.

On one occasion evaporation had taken place in a glass tank containing a lump of' the encrusting tubes, until a large number of' the tubes only had the lower ends submerged. under such conditions the worms survived f'or over a month. Respiration apparently took place through the capillaries underlying the epidermis.

(b) Coverage &. ~.

The ,andy. beach at Taylor's Mistake is very unstable and the lower portions of' encrusting tube masses are subject to periolic coverage by sand. (Yigs.6l & 62). Evidence can be seen of' the death of' the worms due to prolonged coverage. The ef'tect of' coverage was tested experimentally by placing worms in bowls ot aerated sea-water and covering with clean sand. If' the layer was half' an inch or under, the worm is able to push the sand away, f'orming a tunnel shaped depression round the opening of' the tube. Deeper layers tend to pack more densly and the worms are unable to expand their branchial crowns. Consequently. under such conditions the circulation will stop. It was f'ound that worms which had been covered wi th a two]" inch layer of' sand showed complete recovery whEll returned to pure sea-water, af'ter 14?1ng been covered f'or periods up to f'ive days.

(c) 0IY«en def'iciency.

On April 7th a large mass of' the tube encrustation was placed in a small ~ant1ty of' sea-water. covered and lett. f'or tour weeks. At the end of' this period the water was toul and when tested f'or oxy,en content by the Winkler Method showed the barest trace of' oxygen. About 2; % ot the worms were dead, and the gills of' the rest had turned a light brown in colour. although they were still alive and responded to prioking with a needle by retracting slowly. When ~he water was replaced with pure sea-water and aerated the worms showed complete recovery. It was noticed that in many cases the two halves of' the branchial crown were cas' of'f' and a new crown was regenerated. In all oases the colour of the pigment in the gills gradually changed back to the original blue colour.

- 71 -

When the worms were removed from their tubes and various portions of the body were cutf off, such as the abdomen or the collar, the warms responded by autotomizing their branchial crowns. Zoond (1931) and Fox (1938) have found that when the crowns of Sabellids were ~putated the oxygen consumption of the worms fell to 36-37 % of its previous value. Fox also measured the oxygen consumption of amputated crowns and found that the rate was two and a half times that of the whole worm. The high metabolic rate of the crown is probably due to the activityof' the cilia which beat constantly when the crown is expended and the water sufficiently aerated. Therefore, it appears that the crown is autotomized and the metabolic rate reduced while the slow process of regeneration of the other lost parts takes place.

(i v) INFIDENCE OF THE TUBE ON VIABILITY_

Tubeless wor~ can be kept alive indefinitely in fully aerated water. Under adverse conditions, however, they are less viable when removed from their tubes than when intact. In a non-aerated aquarium tubeless worms died within fourteen days, while the worms with tubes remained healthy. In the experiment on deoreased salinity the critical salinity for the tubeless worms was much higher than for those with tubes, between 22-1 and 25-4 0/00 , as compated with between 16-5 and 19-9 0/00.

l ) #

I .,

•

F g . 62. p nks Peninsula .

(i) INTRODUCTION.

- 72 -ECOLOO-Y.

Pomatoceros coeruleus is one ot the most widespread and oonspiouous anImals at the littoral zone at the New Zealand shores. Under oertain conditions it beoomes the dominant organism in ,a relati vel1 large vertical zone. It was decided, theretore, to carry out an ecological study at a suitable locality in order to gain as olear a pioture as possible at the animal in relation to its enviroment, and at the taotors int1uencing its distribution.

As the study proceeded it beoame obvious, that to aohieve this a1m,; . i.e· wou14~~'be necessary to study the OODlllLUJli ty as a whole. To quote trOll MaoGintie (1939): "Every an1:lla1 is a part at the enviroment at every other anw1 in the community, and therefore, is a part ot the enviroment ot the community." A study was made ot the community organization and the relation at one species to another$ The composition at the community was studied in reterenoe to the physiographic teatures at the habitat, tidal t10w and ebb, a.nd exposure to wave aotion.

(ii) GEOORAPRY.AND GEOUlGY.

The locality chosen taD ,the ecological study was Taylor's Mistake, Banks PeniD8u1a • (Yig.62) It was ohosen because all types otshore1ine, trom sheltered to very exposed. were to be tound along a stretch at coast about 200 yards long. Taylor's Mistake lies on the north side at Banks Peninsula to the west ot the entranoe to trtte1ton Harbour and about one and a halt miles tram the sandy beaoh at the southern ot Pegasus Bay. It is a small bay taoing north-east with a sandy beach about 250 yards wide in the oentre. On either side there is a rocky shore ot varied nature.

I¥tte1ton Harbour is a drowned valley and the valley that has been 8ubaerged and drowned was earlier developed by erosion. Banks PeJUnsula was originally an island, whioh began its e%is~nce as twin volcanoes, one having its oentre over the great bowl shaped hollow whieh is now the upper harbour ot z,-tte1ton. Ot the eroding streams that developed one gained a mastery by e%tending backwards to breach the orown torming a 'barranoo'· (Speight 1917.43; Cotton 1941. 44, 49; Davis 1928). hound the periphery ot the volcano the attack ot ooean wavea, working tor long agea. bad developed high vertical clift. which now descend below sea-1eTe1 as 'p1ungi ns cliffs' (Davis 1928). With the melting ot the ice

- 73 -

ot the last glaciation the sea invaded the valleys ot Banks Peninsula and at the same time the bases ot the external clitts became deeplY submerged. The sediment that bas accuaulated at the bases ot these clitts consiats largely ot loess silt washed dow.n fram the Peninsula. This silt does not settle in the normaltashion. Its surtace layer is stirred up by the waves ot every storm, and when it settles it does so into the deepest water available and oomes to rest wi th a level surta ce. Thtla it is never banked against the plunging clittsr and chart. show as deep water below these as is to be tound some miles ottshore.

The volcanic cone is a campositeone built up ot. layers ot lava and fragmentary material. The lava-t1ows and ash-beds are exclusively basic in character; . they vary from. tine-grained basalts· to those in which te1dsltar phenoorysts ~prm a considerable bulk ot the rook. They contain a high percentase ot silica (up to 55 per cent) and normally a considerable amount ot olivine.

The ditterent types and layers ot rooks at T&71or's Mistake have weathered ditferentially into jagged reets and ledges. The angle ot slope varies fram the horizontal to the vertical. In some areas rocks and boulders ot Yarying size cover most ot the inter-tidal zone. Inshore the rock merges into sand at low-atd; but a short distance there are the plunging clitts desoending into the sub-littoral. The sandy beach is subject to considerable change and tixed species on the lower parts ot the rocks are aubjected to periodic cover­ing with sand.

(iii) CIJlIA.TIC AND TIDAL J'ACTOBS.

(a) Tidal data.

The tides are diu:rbal with a range ot about 9·5 :rt at extrame springs and ot about 4 :rt at extraae neaps. The oorresponding times ot high and low water are on an average 24 hours 40 minutes later each succeeding solar day.

Tidal data were oa1culated from. the tidal graphs recorded by the t,tte1ton Harbour Board tide guage. The tigures tar M.H.W.B. and M.L.W.B. were obtained b)" averaging the highest and lowest tides ot both the lesser and greater Spring tides. The same method was used to obtain M.H.W.N. and M.L.W.N. ot the Beap tides. The mean ot the lowest high­waters ot the Neap tides gave the extreme ilowest) high wat.,

q

E.H\l.S. ~~~----------------------------------

,

-,

Fis, 63.

M.H.W.S.

M.H.\J.N. E.H.WN

M.'TL.

E.L.\J.N.

M.L~N.

ML~S.

E.L.\J. S.

Graph of percentage exposure throughout the inter-tide1 zone

- 74 -

neaps (:I.H.W.N.), and that of the highest low waters of the Neaps gave the extrame (highest) law water neaps (E.L.W.N.). The highest and lowest levels reacbed by the greater 8pring tides gave E.L.W.8. and E.H.W.8. The various levels calculated in the above manner are given in the to11owing table.

Tidal scale tor Taylor's Mistake.

I.H.W.S. M.H.W.8. M.H.W.N. E. (lowest) H.W.N. M.T.L. E. (highest) L.W.N. M.L.W.N. M.L.W.S. E.L.W.S.

Ft. above or below C.D.CChart Datum)

(b) Tidal levels ~ exposure 12. !!!:. The importanoe ot exposure to air is a causal taotor

in the vertical zonation ot plants and animals bas been dis­cllSsed bY' Chapma'b (1941) and EVans (194-7). A method ot assessing percentage e:zposure per year at eaoh level has been described by Coleman (1933) andthi. method bas been used here.

Four tortnights were ohosen in 194-8 including two high springs and two low neap. i.e.:

( 1) J' anuarY' 2nd - 16th (Midsummer). ( 2) March 16th - 30th (Aut UlllD8.1 BCJ.uinox). (3) !lay 25th - June 9th (Midwinter). (4) September 15th - 29th (Vernal Equinox).

Far each period the graphs ot the trtte1ton Harbour Board tide guage were redrawn. From. each graph the hours ot exposure at each level tor the tortni~t were calculated. . These are given in the Appendi% Tab18~. By multiplying the total for ~he tour fortnights by the requiSite number ot days the total hours ot exposure at each level tor the year can be calculated and by dividing bY' 8,760 (=number ot hours per year) a peroentage tigure can be obtained. These are shown graphically in :rig. 6).

This graph shows the ~e general torm as those ot Coleman (19331 tig 10, p. 459) and Evans (1947; tig 7, p. 281).

N. I

N.W., to

I'N.E

1.0

w. - - E.

,

~.'W . , , ~.E.

Fis. Sit. ind r _ tor 1948.

- 75 -Chapman (1941) points out that the ditterences in the rate ot change ot percentage air exposure, tram level to level, are most marked in the neighbourhood ot E.H.W.M. and E.L.W.M. This is also true rbD Taylor's Mistake and there are also changes between M.L.W.N. and M.L.W.S. (at C.D. - 0·5 tt) and between M.R.W.S. and M.R.W.N. (at about 6·5 tt above C.D.).

(c) ~.

Fig. ''''is a wind rose tor the year 1948. It will be seen that practically 90 per cent ot the wind,s blow tram between narth-eastand south-west. The winds are generallY ot a strength 1 to 3 on the Beaufort Scale, and, on 97 days out ot 365, winds ot strength 4-7 were experienced. Gales are not trequent.

(d) Ooean currents.

The Antarctic dritt current p8sses up the east coast ot New Zealand until it is detlected ott share by the southern coast ot Banke -Peninsula. A branch ot another warmer current, crossing the Tasman Sea trom Australia, passes through Cook's Strait and reaches as tar south as Banks Peninsula. The tidal wave strikes the south-west coast about 12 0' clock at tull and change ot the moon. It passes through Foveaux Strait and reaches Lrttelton about 4 hours atter its tirst incidence on the coast.

(e) Wave action. _ ................... This varies tram day to day and 100allyWith the

degree ot shelter attorded by reets, ",dlands etc. Taylor's Mistake taces north-east and consequently is exposed to the prevailing easterly winds. It is however, sheltered tram the southerly winds which are generally stronger than the easterly. On the basis ot Moore's (1935) oaloulation tor exposure to wave action a tactor ot 40 is obtained tor Taylor'. Mistake. The action ot the surt is at its maximum on exposed *ocks taoing north-east. On the west side ot the bay, the area near the beach is sheltered tram direct wave aotion b,y a jutting rocky promintor,y. The slope ot the shore also has an ett.lIlt, where this is gentle surt action tends to be less violent.

The coasts ot Banks Peninsula are subjeot at times to considerable ocean swell, especially when the wind is tro. an easterly direction. On the outer coasts this swell is seen to sweep along the shore instead ot curving in and brealdng on the rocks. The absenoe ot shelving tloors at the toot ot the clitts prevents the retraction ot the waves with

.j

'J: f. rn. A. w\. "]: 3'. I\. S. o.t&. n. Q Month." to\Q\~ 0' V"Q.lW\f(l\\ in ,q,,~

.t:.

.100-

tfi)'

. 4(X)'

SO

0 T f m. A. m. . A. 5.. O . . J. -r. No D b W\onth''i total of c:;,UV"\ !t~ne. d U""'~ 1%1

• ~~~~--..-~--~--~~~~--~--------~ F. M. "-. m. -:r. 1: It. . ~. O. M. n

c:... A'ieV"'~'3e W\ontW~ \-e""'peCQ\u~ cl\A.'l"\~ lq4i

Fig. 65. Monthly totals of rainra1l and sunshine, and average monthly temperatures during 1948.

- 76 -

dissipation ot their energy on the shelving beaches.

( t ) RaiD1'al1.

:rig.64 shows the distribution ot rain at Christcll1l:' ch during 1948. It is tairly evenly distributed throughout the year. The annual average raintall is approximately ~(g inches.

(g) Sunshine •

• ~he monthly totals ot sUDshine tor 1948 are shown in Fig.~. The lowest spring tides occur in the atternoons ot January and February. During these months the average temperature is high and the hours ot sunshine reaoh a lD8.%lmum.;

'so the de.iooating etteot ot the sUDshine may be important tor intertidal species.

(h) !!£ temperature.

The m~ monthly air temperatures tor Ohristchurch are shown inFJ.a. t8'c:.The mean annual zoaqe is not excessiv •• Temperatures on the rook surtace·may reach a higher tigure than the surroUJlding air. The maximum. temperature recorded

.on the rook surtace was 290 c. (i) !!!. temperature.

The lowest temperature reoorded was 9°0. in July; the highest 20° C. in January. This gives an annual variation ot 11° C. The highest diurnal variation reoorded was ;0 C.

( 3 ) Salini tl.

Salinity determinations made throMhout the ye~ ~ed little variation, ranging tram 33·3 -/00 to 34·; /00.

, (}iv) D'fHOll:l.

, The araa at Taylor's Mistake was visited at least twice a month tor a period ot eighteen months. This enabled' observations to be made in all types ot weather and under varying tidal oonditions. The relation ot the organisms to the tidal 1.ft1 WIlS studied by the .ethod used by.2 8 (1947). This method involves the direot observation ot tidal heights, and the results obtained by Evans showed a high degree ot accuracy provided, the observations were made on a calm day and the levels checked on ditterent days and at ditterent states ot the tide (springs and neaps'.

- 77 -

Starting trom. high water t the area was horizontally traversed along the water-line, every half-hour during the first and last 90 minutes t and every quarter hour during the middle hours of the ebb-tide. Notes as to the presence and and absence, abundanoe and distribution 01' the various species were made during each traverse. The height 01' each traverse was calculated trom. the table on page 110 01' the Nautioal Almanao. Aotual measurements were also made on vertioal taces.

For the purpose 01' stU4ttug the relationship ot the organisms to tidal level and exposure to air the tollowing species were selected.

AIGAE.

ChlOroibyoeae:-Cod um adherens C.lg.

Phaeophlceae:-BlOssevIIlia scalaris J.Ag. Carphopbyllum maschalo­

carpum Turn. Leathesia diftormis L. Maorocystis pyrifera L.

Rat'sia sp. !aroopbyous potatorum Labill Soytothamnus australis H.et H. Splachnidium rugosum. L.

RhOdoMoea:-Corat=:aa ot't'icinalis L. Iaurenoia sp. PolYsiphonia sp.

AlIIMAIS.

Crustaoea:­Ch8lIIiesiphof;columna

Spengler. Elm1nius modestus Darwib. E1minius plicatus Gray

pO~Chaeta:-omatooeros ooeruleus

Schma.rda.

Mollusca: -lutacomya maoriana

(MYtilua}magellanicus) Iredale. .

Bucoinulum lineum Martyn. Cellana (Heloiaa1sous)

ornata Dillwyn. Cellana radians Qmelin. Lepsia (Thais) lIat18trlDl

Hutton.

LapsielIa (Thais) soobima. Desha;yes.

lIelagraphia (Konodonta) aethiops Gmelin.

Melaraphe oincta Finlay. Melaraphe oliveri Q,. & G. Mytilus canaliculus Martyn. M)tilus planulatus tamark. Notoaomea parviconoidea Oliver. Patelloida corticata corallina

Oliver. ~izellop8is varia Rutton.

I Sypharoohiton pellisGriPentis Gray.

Volsella (Modiolus) neozealan­iaus Iradale.

Tunloata:-Pj'llra pachydermatina

Herdman.

WY

'l3\A

lt \M\"'\,n\A~"':)")V\g

O\A,-\~~~'1")'Od 'O.)t'lhd

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Od C; Y'l+mn d C;"!\A~VoI '3

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,

.

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... ""

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.

.

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,. 66,

The v

ertic

al zo

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at 7

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- 7'0 -

(v) RELATION OF SPEOIES TO THE TIDE L'lVEL AND EXPOSURE TO AIl.

The vertioal zonations ot the various speoies studied are summarized in :rig." This is a picture ot the basic ideal zonation as tound in a reasonably sheltered situation. In ohoosing the locality an attempt was made to eliminate as tar as possible the etteot ot expos~e to wave action. Oonsequently, this basic zonation is oon­siderably moditied according to the degree ot exposure. The etteot ot the breaking ot waves is to torm a 'splash zone'(Ooleman 1933), which raises the tide marks above tEirr level predicted in tide-tables or recorded by tide guages. However, the height ot this 'splash zone' is extremely variable, depending on the state ot the weather and,the oontiguration ot the rock. The influence ot exposure to wave action upon the vertical zonation will be disoussed in a later seotion.

The tollowing table shows the relationship ot the organisms studied to tidal level and exposure to air. This relationship is also summarized in :rig. U.

"-Qble U Percentage exposure

AJ:lae. Vertioal Zonation. to air.

Soytothamnus australis M.H.W.B. to M.H.W.N. 75 to 4.5 Oorallina sp. M.H.W.B. -·3 tt to

below all tide marks 75 to . 0 R~sia ap. E.H.W.N. -·5 ft to

E.L.W.N. - -3 tt. 65 to 30 Co4ium adherens M.T.L. - 1 tt to M.H.W.N.

-·3 ft. 60 to 5 Bplaolmidim rugosUDl M.T.L. - 1 ft to

M.H.W.N. S5 to 10 Leathesia dittormis R.H.W.N. - 1 tt to

M.H.W.N. -·3 ft. 40 to 5 Oarpo~llum mascbalo- E.L.W.N. to below all

carp_ .. tide marks 25 to 0 Blossevillia scalaris E.L.W.N.-·2 tt to below

all tide marks 20 to 0 Macrocystia pyritera M.L.W.N. - 2 tt. to below

all tide marks. 15 to 0 Polysiphonia sp. M.L.W.N. to below all

tide marks 10 to 0 Sarcophyous potatorum M.L.W.B. - ·5 tt to

below all tide marks 5 to 0

Ro's,~ Lower "rf\\ts

~\, . '

(~Ge&'.pt\o ~W:::.ft<.I. l>o~~~s

C odiuf'I" letA

----------

W\'jh\~ f'CIIrl~WI..,~

Wle\(lq +0. e.t'\'V4' 3p.!._ .... -----....!------

Pe. ...... c...e""to.~e. Q"'f>0~U('e.. \-0 ~,("'.

FiS. 6Z.Tha upper and lower limits of the species studied plotted on the percentage exposure graph.

- 79 -

Iaurencia sp.

ji1malS • . #laraphe cincta 'vJl(elaraphe 011 veri

~ilana radians

Notoacmea parviconoidea

~harOchiton pelliser-pentis. .

~esipho columna

viepsiella scobina

Volsella neozealanicus

~Sia Haustrum

~'~lana oraatus ~hizellopsis varia

~lminius plics.us

Pamatoceros coerulus

Myt1lus.'. planulatu$

MJtilus canaliculus

~elagraphia aethiopa

AulaoOJDYa maorica

vi~ius modeatua

Patelloida corticata

~a paob7dernatina

~ucc1nulum l1neum

M.L.W.S. - ·5 ft to below all tide marks

E.H.W.S. - to E.H.W.N. E.H.W.S. - to M~T.L.

- 1 tt. M.H.W.S. - .J ft. to

B.B.W.N. -·6 ft. M.H.W.S. to E.L.W.S.

-·5 ft. M.H.W.S. -·2 ft. to

B.L.W.S. -°5 ft. M.H.W.8. -.7 ft. to

M.L.W ••• M.H.W.N. t ·4 ft. to

E.L.W.N. - .8 ft. M.H.W.N. to M.T.L. -

·7 ft. M.H.W.N. to B.L.W.8.

--5 ft. Il.H.W.N. to B.L.W.8. M.H.W.N. -·2 ft. to

E.L.W.8. M.H.W.N. -.2 ft. to

M.L.W.N. M.H.W.N. -·2 ft. to

M.I...W.N. M.H.W.N. --3 ft. to

M.L.W.S. - ·4 ft. g.H.W.N. - ·7 ft. to

below all tide marks B.H.W.N. -·5 ft. to

M.L.W.S. M.H.W.N_ --7 ft. to

below all tide marks M.T.L. - 1 ft. to

M.L.W.8. - .5 ft. M.T.L. - .7 ft. to

B.L.W.S. M;L.W.S. to below all

tide marks. M.L.W.S. to below all

tide marks

5 to 0

100 to 75

100 to 55

95 to 65

95 to 0

95 to 0

90 to 10

85 to 40

80 to 40

80 to 0 80 to 0

75 to 0

75 to 15

75 to 10

75 to 5

60 to 0

60 to 0

60 to 0

55 to 0

40 to 0

5 to 0

5 to 0

, /'

g/'

I 4. \.

J ~ ./ ~ I . ~ >

~

't!! -.II

lig.

68.

..n )

.... -~

W

,

-" " '\. I ,

.,t/!

If)

':! <::;!

2 <..:P

-.!J ..::t-

~

0 tj't

..Ii ::-; ::t ~

z ~ :t r z ':t. %

t.t..i

...J ~

J:

z ;J. ...i r..J

Z

'.), .....J t:

iii ~

~

z: Ji

::i. .....J L.J

~

0 ') 0 -~ ~ oJ

"> 0 ..,..t;I

0

.... : lJ,.

Grap

h o

t the num

ber o

f up

per and. ~

ower lim

! ts

at th

e vario

us tid

e ~evels.

The

critic

al

lev

els a

re num

bered 1 ~o 6

.

- eo -(vi) CRITICAL DllEIS.

Coleman (193), Chapman (194.1), and Evans (1947), have discussed the significanoe ot critical levels on the shore and the possible factors which may account for them. Such levels have been recognized in the present investigation, and a comparison or une results obtained with those of Coleman and Evans has proved most interesting.

From :Jig. 66 the number ot upper and lower limit's and the total ndmber of species ooourring between - 2 tt and - ., tt, - 1.Stt and 0 it etc., oan be obtained as Col~ (1933, p. 463)has described. These are given in Table )I,­in the Appendix, and trom these figures the graphs in Fig.67 are oonstruoted.

From these graphs the following points may be noted,

(1) There is a maximum number ot lower limits lying between - 1-5 it and 0 tt C.D., i.e. between M.L.W.S. and E.L.W.S. This marks the lower limit ot Elm1nius modestus, Rhizello:psis, varia, Cellana 0I!rarus, Pattelloidea oorticata corallina and liossevilila sea s • •

(2)· Another maX'1ll.um. in the number of lower limits oocurs between - -5 it and 1 ft C.D., or between M.L.W.N. and M.L.W.S. This level marks the lower limit of E1m.inius ~lloatus, Chaaaes~o oolumna, Pamatooeros coeruleus,

ollum. adherens ,!'hesia dltformIs an! !rllius pl&D.ulatus.

(3) There occur's another smaller, ma$um of lower l1m1 ts between 4-·5 between M.H.W.N. and E.R.W.N. The Melarafihe cinota, lIelaraRhe 011 veri occur ere.

though well defined it and 6 it C.D. i.e. lower ll:rUts ot and Cellana radians

t.

(4) On the graph for upper limits there is a martmum. marking the upper limit ot sub-littoral speoie& .between o it and 1·, tt C.D., or betweenE.L.W.N. and M.L.W.N. The brown kelps, CarCphlllma,. Blossevillia, Jlaoroolstis and SarcoRhycus end re.

(,) Another very pronounced maximum ot upper limits occurs between 5 tt and 6·5 it C.D., i.e. at M.H.W.N. This marks the upper limit ot the majority of tilter teeders, barnacles, bivalves and Pamatoceros.

- Sl -

(6) Between 6 ft and 7·5 ft O.D., there is a less well­defined maximum·of ·upper limits. This lies below M.R.W.B • .... (1JIarks the upper limit of Oellan&. radians, Notoacm.ea parviconoidea, Szpharoohiton peiilserpentls and Ob8maesipho oolumna.. .

(7) The minima of the graphs for both upper and lower limits oocur at about )·5 rt O.D., or approximately at M.T.L. This marks the least critical level on the shore for the species studied.

In the region stUdies then, there appear to be six critical levels far the speoies under investigation. These are:-

(1) Between M.L.W.S. and E.L.W.S. (2) II M.L.W .N. and)(.L~'W .S. C) II :M.R.W.N. and E.H.W.N.

14) . Justnabove M.L.W.N. $j :At M.H.W.N. 6) Below M.R.W.B.

" .A comparison of the findings here with those of

Ooleman (193) and Evans (1947) has fielded same interesting results. If the graphs in Fig. 67 are compared with those of Evans (p. )0), Fig. 9) a ma rked similarity in the general trend of the curves and the position of the maxima is noted. Evr;t.ns, however, did not find a marked maximum attthe point numbered 3, i.e. between M.H.W.N. and E.R.W.N.

There appears to be a great deal of similarity between Taylor's Mistake and the locality Evans studied at Oardigan Bay, Wales. He summarizes the climatic conditions in the following words: tIThe climate is typioally northern cold-temperate then and the intertidal region is not subject to great annual variation, generally speaking oonditions may be descibed as mild." If the word northern were to be ohanged to southern the above descripti.on might well be a summary of the local climate. Also the speoies studied by Evans although in most cases of different genera, belong to the same family or order. It would tblls appear that under similar cltmatio and topographio oonditions stmilar species oocupy the same eoologioal niche, possessing in general the same toleranoes as regards exposure to air, wave aotion etc.

The oritioal levels tor Taylor's Mistake are tabulated below tor comparison with those tor Oardigan Bay, and Ohurch Reef, Wembury (Ooleman 1933).

- 82 -

Tarlor's .i~take

1. !i.L.W.S. to E.L.W.S.

2. M..L.W.N. to M.L.W.S.

3. E.H.W.N. - .; ft.

4. M.L.VI .N. - .; ft.

;. M.H.W.N.

6. X.H.W.S. -

7. II.'!'. L.

(Tii) OCllll.UlfiTIES.

Oardigan Bar M.L.W.S. to E.L.W.N.

M.L.W.N. to M.L.W.S.

E.H.W.N.

M.L.W.N. -

M.H." .N. -M.H.W.S. to E.H.W.S.

Ie.L.W.N. - 1·2 ft.

Wembury

II.L.VI.S. -

Not represented

E.H.W.N. -1 tt.

M.L.W.N. -1 tt.

E.H.W.B.

M.H.W.S. - 1ft.

E.L.W.B. - 1tt.

Marine eoology, espeoia1lY the study of the eoo1ogy ot the littoral zone, is ot oomparativelY reoent development. Earlier works on marine lite were developed tram the point ot view of tauna1 zoogeograpb1. The study ot marine oommunities as suoh commenced with Petersens investigations ot the sea-bottom (1913, 18). More reoent work on the rocky shore 1'rom the view-point ot the organization of oommunities, has 811.pbasized more and more the neoessity tor the adoption ot a dynamio viewpoint. (She1tord ~ ToWler 192;; Bigelow 1930; She1tord 1931, 2; Allee 1934; Sheltord et. a1. 193;; Vaughan 1934; T8.71or 193;; Rees 1939; Clements and She1fard 1939). Sinoe a large ~ount of this work on marine oommunities bas been, in a sense, pioneering work there has been a great deal ot variation in the method of approaoh to the probl811..

The concepts and detinitions ot'eoo1ogy as developed b.r Clements and others arose in the first place 1'rom the studT ot plant oommunities. The •• were later adapted to the studY ot animal oommunities on the land. A. muoh more recent development has been the attempt to utilize these oonoepts in the study ot marine communities. It appe~ that many ot these studies have attempted to tit the oommunities into the traaework ot an arti'ica1 olassitication. Besides, there has been a laok ot unitormity in the use ot various terms and oonfusion has arisen 1'rom the use ot various syst811.s. Since eoo10gica1 terminology is samewhatin a state ot oonfusion it is best

- 88 -

to define the terms used in the following disoussion. Biome. The oonoept of the biome is a oomparati ve17 'fl?C£",t­development, Its prinoipal teatures are, tirst17, that plants and animals together oonstitute ecologioal cammunities, secondly, that .the basic unit ot biotio oommunities is the biame with its oonstituent cl~ associations as well as their developmental stages.

OOlDDlunitl. An assemblage ot animals and plants living in, a common locallt7, under s1m.1lar conditions ot en"f'1JK)nment and with some apparent assooiation of aotivities or habits. To quote trom Allee (1927): "Rarely are there plant and animal oamauni ties. Really, there are on17 biotio oOlllllunities, i.e. groups ot plants and animals which are more or less olose17 integrated into a communit7 s7stem. ft

Association. - a climax communi t7 ot releti vely uniform. taxonOilo composition and ph7siogn~.

Fasciation - a portion ot an assooiation based upon a grouping or an absence ot some of the dominant speoies.

Belt - a horizontal17 extended asso~iatlon whiCh may be continuous round the coast or may be interrupted b7 another cammunit7 whose presence depends on slight17 different local oonditions.

Dominants - species which control and cbaraGttrize the cammUD1t7 4irect17 or through their etfects on the habitat, the7 are the common, large, sedent8r7 or slow-moving forms.

Sub-dominants - species having minor control of the oommunity. The~ are neither as abundant nor as uniformlJ distributed as the dominants; but 100al17 may take the place of the dominants.

IIrluents - speoies whioh are significant in the ca.munlty because ot their importanoe in the food chain.

Sub-intluents - less important than the intluents in the (jiiilos or the communit7 because ot less abundance, smaller size, or lack of importanoe in the food chain.

Permanent intluents - wide ranging, motile, animals which produoe sliDIflcant ohanges, chiet17 through predation.

Seoondarl torma - plants and animals ot minor importanoe.

- 84 -

Investigators of the distribution of organisms are divis_ble into 3 classes: (1) Those using thelabitat; (2) those stressing large units and their subdivisions; (3) those emphasizing small units frequently neglecting the large ones. The latter viewpoint is the one adopted by many algologists. Many of these call every patch of dif·ferent algae. covering a square metre or less a different association. In one such studY of an intertidal zone the area was divided into 16 different associations. Such studies are based on a view of the littoral zone when the tide is out and activity is reduced to a minimum. However, as the tide recedt!s, many motile speoies suoh as orabs, starfish and fishes migrate downwards remaining under stones near the low-tide level, and move into these~amBunities and feed as the tide rises. The question is to what community do these belong. The use of the habi .... th8.a::cbeen abandoned by the majority of ecologists. In the present investigation the second viewpoint is the one adopted.

As yet there is no general agreement as to the method of designation of marine communities. The method adopted here is that of naming· the communities after several of the dominant or charaoteristic species (Peterson 19I1). Such designations .should be regarded as provisional on;Ly, and subj eot to change with further study. Other investigators have named communities after the zones of algae; but these bear little relation to the distribution of the animals.

In the investigation of marine communities various workers have st~essed different factors. Same have over­stressed the importance ot physical factors others have over-emphasized the importance of individual life-histories. To gain a complete understanding of the organization of biotic communities all the re~et.nt factors such as environmental int1uences, phYelo1ogica1 lite-histories and the interactions of organisms must be taken into consideration. There is need far tield observations to be supplemented

by experimental work on the tolerances of the different species towards the various environmental influences, e.g., studies of the resistance ot animals at different stages ot their life history (Andrews 1925). The researches of Rice (1935) on· barnacle settlement and survival indicate the importance ot the varying stages in the life-history. Again the necessity tor lefining terms in ecological studies shows the need for the systematizing of the nomenclature. Olearer, mare uniform. and aimp1er detini tions are needed in ecology.

ilus

- 6, -

Studies on the 'littoral rocky shores ot the temperate regions ot the world have shown that these regions are characterized by a barnacle-gastropod-mussel community. The communi ty studied at Taylor's Mists.ke shows a marked ,similaril7 to the Balanus-Li ttorina Biome ot the Pacitic Coast ot North America (Clements & Shelrord 1939). This community may provisionally be termed the Dhamaesipho­MPuilUS-MelaraPhe Biome (Barnacle-mollusc) until turther sUdles revearlts true extent. The biame may be divided into two main associations. Thes. are, the Gh.am.aesipho­MnilUS canaliculus association at the outer exposed shores an the~pho-MytilUa planulatus association ot the more p:r··o areas. Since Pomatoceroscoeruleus is not tolerant ot strong wave action it rarely occurs as a member ot the tormer association except in rockpools, crevices and in the sheltered landward side ot boulders. In the latter association however, it becomes one ot the ,dominant organisms a.nd I propose to deal with this asssciation in more detail and leave a 4iscussion ot the tormer until the section on General Zonation.

CHAMAJSIPHO-Jll'TILUS PlANUIATUS ASSOOIATION.

Dominants and Slow Movi;pg Intluents.

Dominants. dhamiesipho columna, rock barnacle. Pamatoceros coeruleus, spiny tube-worm. Mytl1us planulatus blue mussel. Vol.ella (ModiolU8~ neozealanicus, bivalve. Melaraphe oliveri, periwinkle. Kelaraphe cincta, periwinkle.

Sub-dominants. l1lilnlus plicatus, barnacle. Aulaoamya maoriana (M)tilus magellanicus) Oorallina sp., coralline sea-weed.

Intluents. LepsIa (Thais) haustrum, oyster-borer. Lep.iella (Thais) soobina albomarginata, whelk. Cellana oratus, limpet. aellana radians, ribbed limpet. Xereis australis, errant polychaete.

- 86 -

Ell8.lia miorophylla, errant polyohaete. Asterina resularis,star~ish. Calvasterias suteri, star~ish. S7Pharoohiton pelliserpentis, aeppent chiton.

Sub-influents. loEeaomea parviconoidea, small limpet • • e!agraphia (Monodonta) aethiops, snail. Onohidella nigrioans, Amauroohiton glauous, ohiton. Anthopleura aureoradiata, brown Sea-eneJILDne. 'Cradactie magna, large anemone. Leptoplana brunnea, flatworm. Nemertine sp. . Amphipods. Isopods. Ammothea dobrni, pyonogonid. Allostiohaster polyplax, star~ish. Astrostole soabra, star~i8h. Rhitellopsis varia, snail. 'Desus m.arinus, marine spider.

Permanent Influents. Canoer novaezealandiae, oancer orab. Hemigrapsis sexdentatus, rock crab. Cyc19grap .... lavauxi, rook crab. Eupagurus novaezealandiae, hermit orab. Paramitbrax lateralli, sp1der crab. Petrolisthesel0BBatus, hal~ crab. Diplocrepis puniceus, suoker ~lsh. Acanthoolinus littoreus, spiny .ock~~ish. Clupea antipoda, sprat. Agnost'amus ~orsteri, yellow-eyed mullet. Pseudolabrus celidotus, spotty. TripterY8ium medium. blenny. Tripterysium varium, blenny.

Secondary ~orms. Raffia sp., brown encrusting sea -weed. Codium adherens, green sea-weed. Splachnidium. rugostm1, ~ sea-weed. Leathesia d1~~orm1s, brown sea-weed. Sponges, various species. B)droids, various speoies including Obelia oaught81"yi and Sertul.arians. Aotinia teJl.8broS&, red sea anemone. Anemoniaolivacea, green sea anemone. Patelloida oorticata oorallina, ltmpet. Cr7Ptooonchus porosus, chiton.

- 87 -

Aoanthochiton zealanious. chiton. Guildingia obtecta. chiton. Brl'ozoa, va.rious species. Polyohaetes, 'YBrious species.

The above list is by DO means complete including only the more cammon and important species. A complete list of the speoies identiti.d'~'t'roa 'fal'lor' s Mistake is to be found in the Appendix.

This association extends tram a point about mid­way between M.L.W .8. and M.L.W.N. upwards, and is uncovered twice daily through an extramevertical range ot 8 teet. Below the lower liai~ lies an ecotone, reterred to later as the sub-littoral fringe, composed of species that do not tolerate exposure to any extent and extend dawn into the sub­littoral regions. The distribution of same of the speoies in"-:relation to tidal level has already been discussed. Their distribution in relation to environmental factors will be furt~er discussed in the section on General Zonation.

FASCIATIONS

Within the association there are groupings of the dominant forms to give definite bands or zones, best seen on steep slopes or vertical,races. These groupings may tentatively be termed fasciatioDs, as detined above; but I do not agree with their being regarded as separate associations ~s is often the case. With excessive sub­division the picture of the rocky shore tends to become a static instead of a dynamic one. Five fasciations may be

'recogftized. These are shown in the table belmv with the characteristic species in each. The principal dominant is named first in each case.

THE FASCIATIONS OF THE CHAMAESIPHO-MYTILUS p~TtJS _~SOCIATION. --_. --

I. Melaraphe - Bostrychia arbuscu~ Fasciation. M.H.W.N. - 1 tt upwards.

Melaraphe oliveri ¥elaraphe cincta Bostrychia arbuscula.

2.

3.

- ss -

Chamaesi,ho columna Fasciation. .l.W.N. to M.R.W.N. - 1 ft. Chamaesipho columna Elminius plicatas Cellana radians Ce llana orna t us Sypharochiton pelliaerpentia I..epsiella acobina albomarginata Rafaia ap. Splachnidium rugosum

Volsella neozealanicus Fasciation. M.T.L. to M.R.W.N.

Volsella (Modiolus) neozealanicus Chamaesipho columna Lepsiella scobina albo~rginata

. PomatocEoa coeruleus Fasciation.

. ~:t.W.N. to E.H~~.N.

Mytilus

Pomatoceros coeruleus Chone sp. Sypharochiton pelliaerpentis Onchidella nigricana Euali~ microphylla

planulatus Fasciation. M.t.W.S. to E.H.W.N. Mytilu~ planulatus MytiluB canaliculus Elminius modestus Aulacomya (Mytilus) maorica Cellana ornatus Corallina sp. Petrolisthes elongatus

During exposure, activity within the association is reduced to a small amount of feeding on algae by M. oliveri, M. cincta and Melagraphia aethiops, on mussels and barnacles by tepsiella scobina and to the scavenging activities of Amphlpods, Petrolisthes eloagatus and gulls.

r:'Tide-pools enable some of the inter-tidal organisms to continue ~eeding.

As the water rises, sponges, hydroid colonies, bryozoans, anemones and tunicates begin to feed upon the microse.pic suspension. With the increase in water level, the muss~ls open their shells, the tube-worms expand their gill-~i~ents and both resume straining the water. The various species of barnacles likewise resume their feeding

Obel,,,, ';)e.r\-",\o..ria. etc

. A~,;\e"'\"'o.. «(). \"Q.!);-e("ia..~

c..e..\lo.nC\ notOQ~e.Q.

:'P<:A.re.'\oid.o. s r~Q.roc..."'i ton

Fig. 70, The rood coactions of the Chamaesipho- Mytilus planulatus Association

- 89 -

aotivity. Different species of gastropods Me1araphe, Melagraphia, Rhizellopsis etc., the limpets and the ohltons move about scraping the mioroscopic algae off the hard surfaoes and.the tissues of the seaweeds. Lepsia haustrum and Le!Sielia and various speoies of starfi.sh continue theIr predat on on the mussels and barnaoles. The activity of the scavenging amphipods and isopods increases. Crabs (Canoer Hemigrspsms, CY010Srarsis, Petro1isthes etc.)and fishes fDiplocre&is, AcanthOol nus, Pieugoiahrus eto.) move up the shore wit the tide and feed upon t e wealth of invertebrate life. Llkewise various speoies of PolJcba.t&~ (Nereids, Phy11odocids, Eunicids), and nemertines resume their predaceous aotivities.

The food coaotions of the Chamaesipho-!Yti1us . :(!lanu1atus assooiation are shown in Fig. 10;

(viii) GENERAL ZONATION.

. Eoo1ogica1 studies of rooky shores particularly those of Stephenson (,q~q) and Dakin et. a1. (1948), have shown that the intertidal region oan be divided into a series of -horizontal zones each with its own oharacteristio forms of life~ These zones are related to tidal level and on tb!a basis.can be divided into 3 definite regions.

1. The Litto:ta1 or inter1iidal region. This is the band of shore marked above by the normal high water line of the spring tides (M.H.W.S.). The lower limit is harder to define. Most investigators fix it at the low water mark of the neap tides (M.L.W ••• ), a pOint that may be taken as convenient. .

2. The Supra-littoral. This is the region of the. share lying above M.B.W.S. -Wave action in exposed areas may modit"y this zo~e so that conditions approximate those of the ;lntertidal levels.

3. The sub-littoral Frinse. Between the sub-littoral i.e., the regio;-Covered at all times, and the Littoral there is an eootone which is normally covered except turing the low waters of the spring tides. This region is oharaoteristioa1ly marked by oertain large brown sea-weeds.

The above regions will now be desoribed in detail atalti88 with the lowest level.

Fi 72. it h rocl~ under­i l us can liculus .

- 90 -

(a) THE SUB - LITTORAL FRINGE.

I. The Kell! Zone.

On the open coast in exposed situations the oharacteristic form is the Bull Kelp, Sarcophyous potatorumt The rooks between the holdfasts of the algae are covered by a dense oarpet-of mussels, ~ilUS oanoalioulus. In sem1-exposed positions the Bullp gives way to laorooistis . !H;a. Car~Ol!!!lllum IlaSCbalOcar*um and Bloseevlrla scaler 1&

us canal oulus beoomes less a undant and is replaced ge by the giant stalked ascidian ~~ pachfdermatina.

On the west side of Taylor's Mistake an-rnterest rig suooession of algae oan be traced, trom the sheltered a»e&near the sandy beaoh, along the shore to the open.sea (~i!i ~ The suocession is P01{Sinonia!p.. (red algae) followed by Iaurencia!l?. (re a aeT wlllch is replaced by CarJ)ophyllum, BlossevillIa and Macroclstis and on the open coast sarcopljjcus only is found.

The undergrowth of this zone oonsists mainly of red algae,Corallina !£. and the encrusting Melobesia and L1tho­thamn1on. Characteristic species of this zone are the half­crab, (Petrolithses elonagatus), the large chitons (IUildiI!ia obtecta and dryptoconchus J)orosus), and solitary and colon al tunicates.

II. The Pyura Zone.

Remarkable growths of the stalked ascidian EYura pachydermatina oocur in semi-sheltered situations. The upper limit ot the zone is very regular at about M.L.W.S. i.e. IS inohes above zero tide level. The long stalks are covered with growths of red and brown algae, hydroids and bryozoans. Crawling amongst them are to be found inn_uable small amphipods and isopods (including Hyale ruba, Podoceros cristatus, Scutuloidea maculata and PYniienelIi1[uttoni), ~111ds and pycnogonlds.

- 91 -

LIST OF THE COMMON SPECIES OF THE SUB';;'LITTORAL FRINGE.

AIGAE

PHAEOPHYCEAE:- Myriogloi~ lindaueri XYlin., Papenfussiella

lutea Kylin., SOytosiphon lomentaria Iqngb., Macrooystis

pyritera L., Carpophlllum mascbalooarpum Turn., Saroophyou.!

potatorum. Labill.,

RHODOPHYCEAE:- Lauranoia sp., Polysiphonia sp., Melobesia

Callithamnion sp., Lithothamnion sp., Eupilota formossissi~

Corallina offioinalis L. -PORIFERA

Tethya fissurata (Also several common enorusting speoies not identifiable.)

COELENTERATA BYDROIDA:- Hemitheoa Intermedia Bllgendorf, Sart ular i8 hiED-

~ Gray,

Lendenfeld,

Sertularella orassioula Bale, Sertularella simplex

Obelia nodosa Hutton, Obelia DaughterYi Bale,

Plumularia setaoea Ellis, Orthopy!is delioata !Tebiloook.

ACTlNARIA:- Metridium. phanopteron Parry, Sasartia albooino~

Anam.nia olivaoea Hutton,

Cradaotjs magna

." Cradaotts plic§tus Hutton,

POLYCHAETA Eualia miorophylla Sohmarda, 8tessoa brevioornis Ehlers,

Pbyllodooe oastanea Marenz,

olosterobranohia Schmarda,

sphaerooephala Sohmarda,

Nereis vallata Grube, 8Xllis

Piniosyllis sp., Lumbrioonereis

Adouinia sp., Sabellaria splnulo.~

!~bella sp., Amphitrite sp., Galeolaria gystrix Morch.,

8pirorbis zealanious Gray, 8erpula sp.

- 92 -CRUSTACEA

CIRRlPEDIA:- Elminius modestus Darwin, Tetraclita

~urpurascens Wood, POllictipE!!. s~inuosus Q. and G.

ISOPODA:- Soutuloidea~'maculata Chilt4n, Idotea elongat.a

pynamenella huttoni Thompson, Isocladus armatus Milne-Edwards

AMPHIPOEA:- Podooeros oristatus Thompson, Hyale ~

Ca~rella aeguilibra Say, Par iambus typicus

DECAPODA:- Cancer novaezealandiae Jacquinot and Luoas,

HemigraPfie sexdentatus Milne-Edwards, 'Ovalipes bipustulatus

Plpnotheres ~isum L., Eupagurus novaezealandiae Dana,

Petrolisthes elonsatus Milne-Edwards,

Milne-Ed-,ards.

FYCNOGONIDA Ammothea dobr'n! ~on.

1I0LLllSCA

Leander a:t':t'inis

LAMELLlBRANCHIATA:- Mitilus canaliculus Martyn, AulaoOMla

maoriana (Mytilus magellanicus) Iredale,

Hermanns en , Ostrea renitormls .. Sowerby,

Modiolus impacta

Amphidesma

subtriaBSulata Wood, Paphrua (Paphia) largillierti Phillips,

Protothaca (Pa~hia) crassicosta Deshayes.

GASTEROPODA:- Haliotis iris ,Martyn, Melagraphia (Monodonta)

aethiops Gmelin, Lunella (Turbo) smarasda Martyn,

Patelloida corticata corallina Oliver, O,llana (Heloion1sc"~

~nata Dillwyn, Sisapatella (Cal.zptrea) novaezealandiae

Hotoaamea ~arTiconoidea 011ver, Buccinulua lineum Martyn,

Buccinulum littorinoides Reeves, Neothais scalaris Menke,

- 93 -

Lepeia (Thais) haustrum. Hutton, Xlmeme plebe jus Hutton,

Arohidoris wellingtonensis Abraha;m~

Cheeseman, Aeolida graoilis Kirk,

Glossodoris .ur8amarsinat~

~sp.

AMPHINEURA:- Eudoxochiton nobilis Gray, CrYPtoconchus

porosus Burrow, Acantnochiton zealanicus Q. and g.,

Maorichiton caelatus Reeve, Maorichiton metonamazus Iredal~

Diaphoroplax biramosa Q. and G., Guildinsia obtecta Pilsbury,

Frembleya eeg'egia H.Adams, Amaurochiton slaucus Gray,

Sypharochiton sinclairi! Gray, Ornithochiton neglectu~

Rochebrune.

BRYOZOA Several unidentified specIes

ECHINODERMA~A ASTEROID~:- Astarinareguiaris Verrill, Calvasterias suter!

Astrostole scabra Button, Asterodon miliaris Gray, Allostich-

aster p0lyplax Muller and Troschel.

TUNICATA Aplidium thomsoni Brewln, Didemnum candium'Savigny, PolYci!2!:

Distaplla taylor1 Brewin,

Asterocarpa cel'a Sluiter,

Corella eumyota Traustedt,

Chemidocarpa bicornuta Sluiter,

Pyura subuculata~£luiter, _Pyura cancellata Brewin, Pyura

pulla Sluiter, ~a pachydermatina Herdman.

PISC:ES

Acanthoclinus guadridactylus Forster, Diplocrepis puniceus

Rlchardson,Tripterysium medium Gunther.

z develo p

toceros

- 94 -

(b) THE UTTOBAL.

On the more exposed' coasts t especially on vertical races, t.his zone is inaa,bited almost exclusively by barnacles and consequently may be termed the 'Barnacle Zone-. In the more sheltered 'localities other species or rlxed organisms are round, forming patches.or bands, sometimes to the aLmost complete exclusion of barnacles. However, barnacles are still present betYleen the patches and bands, always occupying the highest regions of the littoral zone. In these sheltered sitUations such as the area studied on-the west side of Taylor',s Mistake the lower regions or the littoral zone is occupied, especially on the more vertical faces, by a remark­~ble growth of the tubes of Pomatoceros coeruleu!, covering

, the rocks to the exclusion of other fixed species. Obser­vations made at various points on Hanks Peninsula, Oamaru, Dunedin and Wellington by myself, and Auckland, Hauraki Gulf, and ~ay of Islands by Oliver, indicate that this tpamatoceros ~t is a characteristic feature of the New Zealand shores.

III. The Pomatoceros ~one.

Pomatoceros coeruleus may be found as isolated individuals or in small groups at almost any level of the littoral zone, except on very exposed faces, provided con­ditions are sufficiently moist. They are present in rock­pools and cracks and crevices, where water collects, from E.H.W.S. to M.L.W.N. However in sheltered areas PomatoCErOS also occurs as an encrusting mass of tubes, closely packed and intertwined, completely covering the rock face. Such an encrustation may reach a thickness of up to 18 inches. On the more exposed shores ~omatoceros forms a similar encrustation on the sheltered landward side of large boulders and stones.

The lower limit of the zone is sharply marked at about M.L.W.N., the region below being occupied by Mytilus canaliculus. On vertical faces the zone extends upwards for about 4 teet to E.R.W.N., with isolated individuals up to M.R.W.N. In semi-e~osed areas Pomatooeros is replaced largely by the blue mussel Mytilus pIanulatus or by barnacles; although small patches and isolated individual tubes, particularly on mussel shells, occur.

This tpamatooeros zone t with its relatively sharp limits presents an interestlngproblem in ecology. The upper limit is probably determined by the amount of exposure to air that can be tolerated i.e. about 80 % exposure. The

ig , 76 . P

Fig . rt7.

toe rOB ererustat10 S on roc at lo.L t s istuke.

eked tub s of tee cr ion .

- 95 -

sharply detined lower limit is ha~der to accoUBD tor. It may be that Pamatoceros required to be uncovered tor a certain period; but it thrives in .oak pools where it is completely 8ubmerged all the time.

The areas that Pomatocer08 oocupies are also favours. ble for the growth ot barnacles and mussels. The most probable explanation of the presence or.absence atlmese forma in different localities is to be found in the relative sensitivities ot the different larvae at the ,.t1od ot 8ettle­mente Mussels,barnaclea and Pomatoceros all have pelagLc larvae; but mussels and barnacle larvae possess speoial attachment organs enablin« them to attf,loh themselves in ar eas subject to strong wave action. Speoial attachment organs are not present in the larvae of Serpulids. Sergrove (1941) found that in cultures of the larvae of Pamatoceros trigueter reared ·in plunger-jars the larvae settlea in one region only, viz. the angle between the sides and the bottom of the jir, i.e. in the region of least disturbance. Rock faces sheltered "tr·om the direct wave action would therefore favour the settling of Pomatocer08 larvae.

~n these encrustations the tubes grow out more or less at right angles to the rocks and are so closely packed that when covered the gill filaments form a dense blue carpet. The interstices betwwen the tubes catch a consider­able amount of sand, broken shells eto. Imptytubes, and the spaoes between them, form the habitat for 8. unique and VEIl' y rioh community in whioh Pomatooer08 can be regarded as a

true dominant. In this oommuni ty there are several spec ies that appear to be so closely linkel with Pomatooeros, that they have not been found elsewhere, or if so, extremely rarely.

Between the tubes there is a rioh scum of diataas and unicellular algae and encrusting bryozoa are cammon. The encrustation is not altogether favourable tram the development of oreeping sedentary molluscs suoh as ltmpets,. and large algae are almost completely absent. !he follow1Dg list gives th~ names of the species torming a well-balanced oommunity. Partioularly noteworthy is the large nmnber of polyohaete., the majority of' which can only be found by break­up a lump of the material in sea-water.

- 96 -

LIST OF SPECIES CLOSELY ASSOCIATED WITH THE 'POMATOCEROS ENCRUSTATlbHS

COELENTERA'!\ AcrrINARIA: - Sasartia albocincta :utton~ Anthopleura minima Jh L;

Hutton, AnthoPle~a aureoradiata Itucky, Thoe dla~hanes Parry_

PIATYHEIMIlft'BES Leptoplana brunnea Cheeseman.

!?~:w.atTLOIDEA PhygosQ!!1A, §rmul&~:um.::: 0"" .

POLYCHAETA ERRANTIA:- Euphionel18 polycnrama Scbmarda, Eualia

microPhylla Schmarda, EusUa sp.,

Ehlers, ?bYllodoce castanea Marenz,

8tesgoa brevicornis

Phtllodoce sp.,

Podarke ausustifrons Grube, Bereis australis Scbmarda,

Bereis ruticeps Ehlers, Bereis maoriea Benham, Bereis

neozealanica Benham, 87l1i8 closterobranehiata Scbmarda,

Syllis sp., 81llis ap., Slllis sp., Slllis sp.,

Pinios;rllis sp.,

monoceros Ehlers,

Exogone heterochaeta McIntosh, Aut 0 lytus

Grubea sp., Mar~hysa sp., Lumbrico-

nereis s~haerocephalls Scbmarda, Lumbriconereis sp.,

Stauronereis sp., Glyee,a ovigera Scbmarda.

SEDENTARIA:- POlYdora monalaris Ehlers, Scololepis sp.,

Cirratulus ~uchalis Ehlers, Adouinia sp., Chone sp.,

Amphitrite sp., Sabellaria spinulosa Schmarda, Serpula sp.

NEMERTINI Several unldentil"ied species.

ARACHNIDA Desis mariana Hector.

CRUSTACEA AMFHIPODA AND ISOPODA:- Several species.

- 97 -MOLIDSCA

Mytilus planulatus ramark, Volsell~ (Modiolus I neozealanicus

Iredale, AUlacamya (Mytilus) Maorica Iredale, Not oa cmea

Earviconoidea Oliver, Rhizellopsis varia Hutton, Gadinia

nivea Hutton, Onchidella nigricans Q. & G., Acanthochiton

zealanicus Q. & G., M~orichiton caelatus Reeve,

Sypharochitbn Eel~iserpentis Gray.

J3RYOZOA Several encrusting species.

TUNICATA Pyura Eulla Sluiter.

Of the animals listed above a special note is desirable as tar as the follovdng species are ooncerned:

Desus maria~,_ Yhoe diaphanes, Phyoosama annulatum,

Chone sp., Polydora monalaris, Gadinia nives and

Onohidella nigrioa~.

'The Marine",sl;ider. Desus mariana Hector.

The ocouranoe of thi3 spider is particularly interesting. Robson (lSS7) first found this speoies at Cape Campbell where it was found in 'L1thodomus' holes in rock. Dakin et. ale (194S) report a similar species Desus crossland! building a similar web nest between intertwined GaleoIarIs tubes. Several other species of marine spider are recorded but as yet their behaviour has not been investigated fully and nobody has observed them feeding.

~hoe diaEbanes Parrl. Sea anemone.

This .is a small transparent oolourless sea anemone found hanging on the underside of buldging encrustations. It has no't been found elsewhere at Taylor's Mistake.

PhyoosOfllB. annulatum, Sipuncq,lid •

. 'This Sipunculid has only been found either embedded

- 98 -

in the sand between the tubes or f"requenj;ly oooupying empty tubes. As far as oan be asoertained it has not been reoorded fr~ suoh a habitat.

Chone sp. and Polydora monalaris Ehlers.

In the lower half of the Pomatooeros enorustations the Sabellid, Chone ap. is very oammon between the Pomatooercs tubes. ~lydora. monalaris is a small Spionid, about half a m m. in l6ngth, ooourring in large numbers between the tubes. These two species are numerioally the most important Poly­chaetes"apart fram Pamatooeros in the assooiation.

Gadinia nivea Hutton.

This interesting Gastropod (Pujmonate) has only been found on the roof of small holes in the enorustations. Wearly all the specimens found have a Pomatoceros tube ooiled round the apex of the shell.

Onohidella ni~rioans g. & G.

Although found elsewhere this air breathing Gastropod isa regular and oommon Inhabitant of the Pomatocel'Os enorustations. ,Dakin et. ale (1948) report a similar speoies Onchidium patelloides Q. & G. , as being charaoteristic of the Galeolaria encrustations on the New South Wales coast.

Fig , 78 , A generel or the rnacle Zon ,

-99 -IV • The" Barnacle Zone.

The development of this zone depends on the degree of exposure to direct wave action and on the con­figuration of the Tock. On the very exposed coasts, espec­ially on vertical faces, the littoral zone is populated almost exclusively by Ohamaesipho, forming a close mat with the individuals touching each other on all sides. The effect of direct wave action is to raise the upper limits of the various zones. This is especially evident on sloping faces where the waves run up the shore as they break. Rere the upper limit of the barnacles extends up to 20 feet above the upper limit of the sub-littoral whioh is also raised about 18 inches. OhamaeSi~ho oolumna covers the rook sur­tace up to about 9 feet, wI h a few extending up to 12 feet. Above its optimum upper limit it is replaced by Ohamaesipho brunnea. lIoD.'be (1944) notes that when O. columna and O. orunnea meet they dominate separate but-overlapping -commuD1ties the former always above the latter.

Where the rock surfaoe is of a broken or rugged nature, providing a degree of shelter from the dir$ct wave action, conditions may be favourable far the development of other species. ~ilUS R±anulatus may occur up to 12 feet above the upper 1 t ot the sub-littoral, and above it Vol­sella neozealanicus extending up a turther 9 feet to wi~

3 feet ot the upper limit of Ohanaesipho columna. Poma-toceros coeruleus may also occur in orevioes where water collects up to a height of 12 feet.

In localities that reoeive protection from direct wave action, and may be regarded as being semi-exposed, the barnaoles are largely replaced in the region of the littoral zone by other sedentary species. Exteading from the upter limit of the sub-littoral up to a point midway between • M.R.W.N. and E.H.W.N. there is a zone occupied mainly by MAjilus planulatus and Ohamaesipho oolumna. Soattered ~re an there and sometimes forming patohes down to M.L.W.N. is th.e larger barnacle Elm1nius plicatus. Po_tooeros oOElUleus is also tound forming patches, O~ as isolated individuals --­on the rooks surface or on mussel shells. The small bivalve, Volsella (Modiolus) neozealanicus occurs in the upper part ot this zone trom I.T.t. up, extending for a ahort distance into the upper zone of the littoral. This upper zone is characterized by the barnacle, Chamaeaipho columna. Other characteristic species of the upper littoral zone are the two species of periwinkle, Melaraphe oliveri and Melaraphe cincta and the limpet··-Cellana radians. Here the

FiB . 80 .

Zon t Ch

M Ius, Vo s 11a and Zones.

J.luB lanula u growing' a s~eltered os o.

i-

- liD -,the mat-like red alga') Bostrichia arbuscula otten,torms a conspicious band about Is inohes wide. .

In the lower zone ot the littoral,Tarious species ot algae otten torm oons];lcious bands or patches. Tufts at Scytothamnus australis are tound trom M.H.W.N. to M.T.L. and patches ot Codium ;dherens oover the rook surtaoe over a vertical range ot teet 6 inohes. A brown enorusting alga' RatsiaYu..o:rten torms a well-J;IlB.rked band extending 18 inohes on eIther side ot M.T.L. and a sUb-littoral speoies ot QJl~-. llina covers sloping taoes up to R.H.W.N.

TWo very oharacteristic species tound right through­out the Littoral zone up to II.H.W.8. are the chiton, Snharo­

. ohiton Eelliserpenti8 and the small limpet, :loto.cmea par'Vic­onoldaa. There Is an inter"~1D& succession ot the various

. species at limpet found throughout the littoral zone. Cellapa radians is charaett.ristic at the upper zone,being replaced in the lower by' Cella~ Ornatus. From. a toot above E.L.W.lf. another species, Ptte~ida corticate corallina, always covered with a pink corall ne seaweed,is cammon,extending down to the upper limit ot the sub-littoral. In moist sullies especially in the band occupied by the enorusting algal Ratsia ~., the pulmoDates)Siphonaria zealanica and Benbamina obligua!a, and Onchidella nl!{lCanS are common. The herbIvorous .... tropNa UelagraEhia ae hleps and Lunella (Turbo)ijtfdara, are -chiraoterietic ot the lower hiit ot the ttorai. The earn! Toroua whelk Lopaia (~.l ;U8trUIII is found 1'r0lD M.H.W.N. down and tne smal er Le'8~ (Thais) scobina albomarsinata is to be tound in cusers, when the tIde is out, trom a toot below M.T .L. to above M.H.W.N. At various places along the shore a colour variety,~. scobina rutilia is quite common.

In the more sheltered localities the littoral zone tram M.L.W.N. to R.H.W.N. is occupied by the Pamatooeros encrustation discussed above. Above there is a band at Volsella (Modiolus) neozealanicus, about 2 teet in width, with a tewl(itIlus planulatus and ~niUB Elicatus in the lower halt of the band. Above th s band t e rock surtace is oovered with Chamaesipho columna.

In cracks and channels where water remains,two species ot anemone, Anthopleura aureoradiata and Anemonia oliv.cea are very common, and In the lower halt at! ill.::, d

lIttoral , especially in orevices where sand colltcts, are the large cradact~ magna and the smaller Cradaotll plicatus, both ~utliged ~th small pieoes of shell and sand-grains.

Fig . 81. P toccros coeruleus and Chamaesipho columna .

Fi 82 The large rnac niu9 L.c 9.

_ 101 -

LIST OF COMMON SPECIES FOUND IN THE BARNACLE ZONE

ALGAE CRLOROPHYCEAE:- Bryopsls plumosa C.Ag.,

Codium adherens C.Ag., Cladophora sP.,

Bryopsis .estita J.Ag.

Chaetamorpha darwinii

Kuetz., Ulva lactuca rigida C.Ag., Enteromorpha Minima Kuetz.

P.BIEOfHlaEAB;- Ectocarpus conifervoidea Roth,

horda.ea Harv., DictlotA dichotoma Ruds.,

Halopteris

Zonaria subartit-

ularta Imx., Rafsia sp., Leathesia diffOrmis L., Splacb-

nidium rugosum L., Desmarestia firBa 'C.Ag., Ilea fascia

Muell. ,

Bory,

Colpamenia sinuosa Roth, Adenoclstis utricularis

Scytothamnus australis H. et H., Rormosira banksii IUrn

RHODOPHYCEAE:- Caulacanthus spinellis Kuetz, Gelidium

ceulacant~ J.Ag., Bostrichia arbuscula H. et H., Het er 0-

siphonia cincinna Fkbg., Callithamnion sp., Euptilota

rarmossissima Mont., Melobesia sp., L1thothamnion sp.,

Corallina officinalis L., Coralline sp.

COELENTERATA

HYDRROZOA:- Sertularia bis~inosa Gray, Sertularella simplex

Lendenfeld, Obelia caushterli Bale., Plumularie setacea Ellis

OrthoPlXi. delicata Trebilcock.

ACTINARIA:- Metridium phanopteron Parry, Actinia tenebrosa

Farquhar,

Stucky,

Anemonia olivacea Hutton, Anthopleura aureoradiata

Anthopleura inconspic~ Hutton, Anthopleura minima,

Cradactus masna Stucky, ..

Cradaot:lS pLlcatus HuttoD, Thoe -diaphanes Parry.

PIA TYHEIMINTHES Leptoplana brunnea Cheeseman.

IS, 13. The Barnacle Zo~e. F.lmlnius eipho columna and Volsella

llcatus , C 0-eoz 61 i \..8 .

- 102 -

NEMERTINI Several unidentified species, a pink one being very oammon.

PO LYCHAETA ERRANTIA:- Euphionella POlyohroma Sobmarda, Eualia micro-

phylla Schma~da, Nereis australis Scbmarda, Nerels vallata

Grube, Nereis neozealanicus .Benham, Lumbrionereis

sphaerocephala Scbmarda.

SEDENTARIA:- Cirratulus nuchalis Ehlers, Adouinia sp.,

Sabellaria spinulosa Grube, Amphitrite sp., Sabella sp.,

Pomatoceros coeruleus Schmarda,

'~\Spirorbis zealanicus Gray.

CRUSTACEA

Galeolaria hystrix Morch,

CIRRIPEDIA:- Chamaeslpho columna Spengler, Chamaesipho

brunnea Moore, E~inius plicatus Gray, E~inius modestus

Darwin, Tetraclita purpurascens Wood, Pollicipes

spinuosus Q, & G.

DECAPODA:- Oancer novaezealandia Jacquinot & Lucas, ~-

grapsgs sexdentatus Milne-Edwards, Cyclograpsis lavauxi

Milne-Edwards, Paramithrax latrelli Miers, Pinnotheres

pi sum L., Eupagurus novae-zealandiae Dana, Petrolisthes

elongatus Milne-Edwards.

FYONOGONIDA Ammothea dohrni Tham~son.

MOLLUSCA ~LLIBRANCHIATA:- pytilus canaliculus Martyn, Mztilus

planulatus Lamark, Aulacomya maorica (Mytilus magellanicus)

Iredale,

Sowerby.

Modiolus impacta Hermannsen, Ostrea reniformis _--,

- 10) -

GASTROPODA.: - Melagrapb1a ( )(ODodonta )aetb10Rs Glael1D,

Lunella ( 'l"urbo) saarasada ~tJU, Pate110ida oortiea,,· f:'

ooralliDa Oliver, Kotoaemea :parTiconoidea Oliver, Oe1]&n6

(Helcioniscus) radIans GIIlel1n, Cel18Da (Helcionlsou8) ornatA

Di111Q1l, Ce1lana ornata inoonspiouus Gray, Melarapbe

olIveri Finlay, Melaraphe cincta Q. a. G., Rhize110psis

varia Hutton, Lapsia (Thais) baustrUlll. Hutton, Lepsiella

scobiD8~ ~.1 bamarginata nesbe:yes, Lepsiella soobina rutil1a

Suter, Siphonaria austral1sQ.&&9., Sipbonaria zealanieus

BenhaJnina obl1gua-ta SCM'erby, Gadinia Divea Hutton,

Onobidella nisrioans Q. & G.

~:- Acnathochiton zealanicu8 Q.& G., MaorI chiton

eaelarus Reeve, Amauroohiton Slaucus Gray, SJPhar.Ohi,~

pe11Iserpentis Gray, Sypharoohiton sinolairi Gray.

ECHIBODERMA'1'A ASTEROlDA;- Aster~ reSUl8ris Verrill, 8uter! LOriol.

1fmIICIA'f.l

Ca1'Y8.sterias

~se are~ found mostly In the lower region under aou1ders or aD. the loof of overhanging caverns.

AplidiUlD. thoaonsl Brewin, Didemnum oandiua SavigJl.7, POlleltor

sP., Distaplia tay10ri Brewin, Corella eumolla !raustedt,

Asterocarpa ~ SlUiter, Ohem1dooarpe bIeornuta Sluiter,

Pyur8 eancellata Brewin, flura pulla Sluiter.

PISC! '1'ripteryslon mediUm Gunt~r, Trypterlg10n variua Forster,

Acantboclinus gua4rIdaotylu8 Forster,

Richardson.

Diploorepis punioeus

~~ __ ~4~. The Supr~-littolal. roc ~ ere ice.

~~~.~~e~. ollver1 1n a

- 104 -

'1m SUPRA LITrORAL.

v. 'lihe Melaraphe Zone.

The highest zones ot the rooky ahore, aboTe M.H.W.S., are oocupied almost exclusivell'bl' two species ot Gastropod, Melaraphe oliveri and Melara,he cincta. The width ot this zone depends on the etfect 0 wave action. On exposed coasts where there is considerable splash specimens ot Melaraphe eincta may be tound up to 40 teet above .M.L.W.S. Both species extend down into the littoral, Melaraphe cincta down to E.H.W.N., with the optimum lower limit or Melaraphe oliveri at M.T.L. - 1 tt. with a tew extending down a turther 18 inches. Melaraphe oliveri usually does not extend up as tar as Melaraphe cincta.

H

Fig

. S5.

The b

asic

Zo

natio

n o

f the sh

ore an

d som

e v

aria

tion

s. E

xp

lanatio

n

on

pag

e op

po

site.

Explanation of Fig. 85.

:~. The zonation as found on the open &xposed ooast.

II. The typical zonation of the ChEmaesipho-Mytilus planulatus assooiation as found in semi-sheltered looalities.

III.The zonation in areas where the Pamatooeros enorust­ations are developed.

- 105 -

(ix) DISCUSSION.

Pram investigations in Great Britain by Coleman (1933), Kitching (1935), Evans (1947), etc; in South Africa by Stephenson (1939); in Australia by Dakin at. ale (1948) and in North Amerioa by Huntsman (1918), Hewatt (1937), Sheltord (1936) etc., it is clear that there is a funda­mental basic zonation of typical indicator animal species cammon to the temperate regions of the world. This basic scheme is, a l1ttorina zone occupying the highest level, followed by a ~rnacie zone below with a Laminarian zone oocupying the region de?Ined above as the sub-llttor~inge~

These zones as suggested by Stephenson (19J7) could be defined on the basis of exposure to air. ~or the-two localities where accurate information on exposure is avail­able, i.e. Cardigan Bay, Wales, and that covered by the preaent investigation the Sub-littoral frinse lies between . 10 /0 and 0 % exposure, ue Barnaole zone between 90 ~ and 10 % and the Llttorina zone betweeilIlrO % and 90 ~ /0.

~,;...;..;;..;;...,o;;; ............. _

The Sub-littoral r.ringe is occupied by the large brawn kelps, Ecklonia and Phyllospora in New South Wales, Eoklonia and tamlnarla etc.-rn South Afrioa, Laminaria in Ens lind , laIninarla ana Fuous in North America, SarcQiLhycu8

in Tasmania and southern Australia and SaroophlCUS, DUrvellla, and Carpophyllum. in New Zealand. A 'ful'a zont has also been reported from New South Wales and South Africa as we1. 1 as from New Zealand.

The Pamatoceros zone has its oounterpart in the Galeolaria zone of New South Wales (Dakin et. al. 1948). Stephenson reports Pamatoleios crosslandi fOrming oonsid~­able tube masses along the southern and eastern ooasts ot South Africa. Various species of Mytilus are oharaoteristio of the shores of Tasmania and Southern Australia, North Amerioa and Europe.

As mentioned before,.ertain eoological 'niohes' are of universal or widespread ooc~ce, ocoupied in different coasts by different speoies having the same general requirements. The correlation of these 'niches' would be an interesting study.

It has been shown that the distribution of the various species on the shore is related to tidal level and the degree of exposure. The levels ocoupied by the different speoies are modi~ied according to the degree of exposure to

- 106 -

. -wave aotion. Unfortunately the effect of wave aotion oannot yet be measured quantitatively, as a whole oomplex of subf\t~ary effects are involved. In order to understand the ada~ion of littoral species to their particular zone on the shore, a thorough study of their physiology, especially with regard to tolerance to adverse faoto~s)is needed.

- 107 -

22. GENERAL DISCUSSION.

From a study ot the anatomy or Pomatooeros ooeruleus and a oompa~ison with that of other SerpulIds it Is apparent that it is one of the most highly developed representatives ot the group. The body struoture is highly modified for a sedentary tubioolous existenoe. This is well seen in the reduotion of the oiroular muSoles and the compact arrange­ment of the longitudinal muscles into definite bands, enabling quick withdrawal into the tube. This modification is also seen in the nervous system, where the giant fibres of the ventral nerve cords are enormously enlarged, forming over he. If the bulk of the cord. The giant fibre forms a huge syncytial axon which enables the animal to act as a unit in quick withdrawal from noxious stimuli. The adoption of a sedentari mode of lite, with abolition of the need for the more complex patterns of behaviOUD, charaoteristio of free-living forms, has permitted this specialization of the oentral nervous syst8lll; This specialization, however, has led to a restriction in the range of responses possible.

The advanced features shown by Pomatooeros ooem leus are, the very much enlarged thoracic nephridia, the well developed branchial crown with its complex ciliary feeding mechanism and the well defined blood system with its blind­ending oapillaries.

In the simpler Serpulids the nephrid~a have the fora of a simple glandular aac opening by a nephrostome into the peristomial coelom. In Pomatoceros the nephridium is differentiated into derinite regions, the ciliated tube and the glandular sac with its oaaplexly folded wall, extend­ing t~ough the length or the thorax. The blood supply to the sao also is more highly developed than in other Serpulids, and the emptying of the sac is brought about largely by the action ot the oiroular musoles surrounding it. In the Serpulids with the simpler nephridia the lateral and median ducts are oiliated, the emptying of the sao being brought about by ciliary aotion.

The branohial orown with its large number of filaments shows a more complex struoture than is found in the majority of Serpulids, and its food colleoting mechanism shQWs a marked resemblance to that of Sabella Eavonia (Nicol 1930). This resemblance is seen in the development of the basal membrane, uniting the bases ot the gill filaments and of the basal folds, enabling the sorting of food particles according to size. It would appear that the so-oalled branohial orown is primarily a food oolleoting

- 108 -

structure and that the respiratory function is secondary. In Sabella the crown accounts for two thirds ot the oxygen intake; but Sabella is an advance form having a well developed blood system. A comparison with the more primative members of the Sabellitor.mia would be interesting.

The blood system ot the species studied presents many interesting aspects. The blood pigment chloroeruorin which is possessed onlY by Sabellid, Serpulid and Ohlorbaem1d worms has been extensively studied by Fox in Sabe!!lds and to a lesser extent in Serpulids. As a trans­porter of oxygen the p1gment is highly efficient; but its high molecular weight may account for its restricted occurance. Unlike the more pr1mitive Serpulids Pamatocaos coeruleus possesses a well developed blood system ot weI! defIned Tessels with definite circulation. Lang (1904), Lee{ (1912) and Hanson (1949) consider that. the primitive Annelid possessed a blood system consisting of a gut sinus lying between the gut wall and the peritoneum, with septal and mesentwric sinuses communicating with it. These sinuses have developed trom the blastocoel. ,In Filograna implexa the blood system consists of a system of sInuses as outlined above, with detinite vessels only in the anterior region. The restriction of the sinusoid spaces to circular canals led to the formation of definite vessels as found in Pomatoceros.

In Sabellids and Serpulids the capillary endings of the vessels end blindly and do not anastomoze with each other. The tunction of these structures is not yet clearly understood. All the blood vessels have well developed muscular walls containing fibres arranged transversely to the long axis of the vessel. The blood is moved along the vessels by rhythmic peristaltic contractions. The various vessels have differing periods of contraction, so arranged that. the blood, when expelled from a Tessel and its capillaries does not flow back agaln. One gains the

/ impression, that in spite of the blind-ending vessels, the circulation about the body is an active one. The lack of vessels among the muscle blocks is noteworthy. Their presence in the muscle may interfere with the quick contraction necessary in a sedentary tubicolous animal. The muscles must obtain their oxygen trom the coelomic fluid into which project large numbers ot the blind-ending capillaries.

Another interesting aspect ot the blood system is the problem of reversible stoppage which appears to be fairly widespread among invertebrates. Since the worms

- 109 -

are uncovered daily for a considerable period the blood circulation will be stopped while the worms are retracted within the tube. They are also able to survive coverage with sand fot a period of up to seven days. During this period they must respire anaerobically. Experiments oarried out by Fox' with Sabella and in the present investi­gation with Pomatooeros appear to indicate that the stoppage is due to the accumulation'of carbonic aoid in the blood and that it is not under direct nervous oontrol. In Pomatooero8 the ciroulation is inhibited by oxygen-free sea-water; although the reaotion is not as rapid as with oarbon dioxide saturated sea~water. Sabella, on the other hand, does not respond to oxygen-tree sea~water. Whether thiS' reversible stopp~ge has an adaptiye funotion J

or not, is not olear. It may be that the stoppage reduoes the metabolio rete while the worm is withdrawn into the tube.

The torm of xhe tube in Pamatooeros ooeruleus is very variable and the differences appear to be correlated with the growth habit ot the tube and; not due to any peculiarities of the substratum or the physioal or chemical oonditions of the sea-water. Remarkable growths of encrusting tube masses are formed in various regions of New Zealand. For their development shelter trom direct wave action is necessary, and i;n Banks Peninsula they are best developed on more or less vertical faces. If the tubes from these enorustations are compared with those of worms growing singly or in groups on rock, shells etc., they are so markedly different that they appear to belong to separate species. Correlated with this difference in the structure of the tube there is a modification of the collar fold.

In this investigation the Chemical nature of the tube and the aragonite nature ot the calcium oarbonate haW~ been determined. The veIls responsible for the formation and secretion of the tube material have been detected and the process ot tube formation has been followed. Pamatoceros coeruleus is so easily kept in the laboratory and so abundant that it would prove very suitable for more extensive experiments on the physiology of calcium carbonate secretion. Evidence has been collected that points to the sea-water as the source of calcium, the calcium secreting cells extract­ing the mineral trom the blood. The development of the calcareous plates that seal off the posterior ends of the tubes has been followed for the first time and it has been shown that the worms are capable of repairing damage to the tubes.

- 110 -

The development of the worm from the fertilized egg to the fully formed troch~sphere has been followed. It has been found that eggs and sperm are produced throughout the year. The specialized nature of the trochosphere has been pointed out. The egg is small, with little yolk and development is extremely rapid. Indications are that the larval period is of several weeks duration and consequently locomotor and feeding structures are well developed. The protracted pelagic life is comparable~ith that of the other dominant sedentary littoral animals, such as mussels, barnacl~s and limpets.

Occ~ing as it does in large numbers on the littoral shores, Pamatoceros coeruleus will have an important influence on the Chemical and physIcal properties of the sea-water. As a result of its filtration activities large numbers of bacteria and other micro-organisms will be removed from the water. It is found in both clear and turbid waters. Any material that is too large to enter the basal folds of the filaments is entangled in mucus, to form ropes or strands of material that are rejected. This may have a considerable influence on the physical properties of the water since large quantities of suspended matter may be removed.

The excretory and respiratory products of the worms will be' utilized by the phyto-plankton and bacteria of the sea-water. After death the calcareous tubes gradually dissolve and the component elements are retunned to the sea-water.

In the food-chain ot the association to which Pamatoceros coeruleus belongs it acts both as a producer and a oonsumer. It removes phyto-plankton, bacteria and minute protozoa trom the sea-water. It in turn supplies animals such as birds, fishes and molluscs with nourishment. The worms produce eggs and sperm throughout the year and these contribute towards the food of other tilter feeders. Also the larvae which have a prolonged pelagio existenoe turnish a considerable part of the tood supply of other animals in the vicinity. A large population of oommensal ciliates teed on rejected partioles, taking advantage of the water ourrents created by the worm.

A detailed study of the littoral zone at Taylor's Mistake, Banks Peninsula has been made. For comparison with Pomatoceros the vertical zonation~ot a number of species of plants and animals bave been worked out. From this study it is clear that there are certain levels on the shore that may be regarded as critical far the species under investigation.

- 111 -

The upper limit of Pomatoceros coeru1eus coincides with that of E1m1nius p1icatus, ~i1us,p1anu1atus, Volsella neo-zealanIcus. ThIs po~ lies at M.R.W.N. and appears to be critical for the majority of filter feeders. The lower limit also coincides with that of the barnacles and M~i1us p1anu1atus. This lower limit of Pomatoceros is very clear cut. A compar­ison of the cittica1 levels recognized in the present investi­gation with those found by Evans for Cardigan Bay, Wales has proved very interesting. The general coincidenc~ of the critical levels is very ~ked. It appears that where there are the same general ecological conditions, the 'niches' are occupied by similar species which may belong to different genera' or orders and even to different families.

. . A study has been made of the cammunittin which

Pomatoceros coeru1eus is one of the dominant organisms. The remarkable encrusting growths of closely packed tubes form the habitat for a unique community living between the tubes and occupying the empty tubes. The pDotection afforded is particularly favourable for the development of large numbers of small delicate Po1ychaetes such as Syllids and Spionids. The large~ carnivorous Po1ychaetes are also numerous. The total number of species found among the tubes is over thirty. A number of species of animals are closely linked with the encrustations being rarely found elsewhere. Particularly notewDDthy are the marine spider, Desus mariana, the sipuncu1id, p~cosoma annu1atum and the gastropod, Onchide11a nistlcans. ~mIlar encrustatIons have been reported trom the coasts of New South Wales; the Ga1eD1aria zone with its associated specie. presents ma~ marked resemblances. The development of a Serpu11d zone in that region of the littoral usually occupied by beznac1es and biva1.es appears to be confined to the temperate regions of the Southern Hemisphere.

The general zonation of the littoral zone has been discussed and comparisons have been made with investigations carried out in various regions of the world. From these investigations it is apparent, that there is a fundamental basic zonation of the littoral zone that is common to the temperate regions of the wor14. With the recognition of this basic zonation there is a standard for comparisons between the littoral regions of different areas. This basic zonation is subject to modification by exposure to wave action, rock configuration etc.

- 112 -

APPENDIX - I-

TABLB Jt: NUMBBRS OF UPPER AND LOWER LIMITS AND OF

TOTAL SPECIES AT DIFFERENT SHORE LEVELS_ •

Ft. above or No_ or No_ or Total No_ ot beIow ~_i5_ Upper Limits_ Lower Limi ts_ Spec1es_

7-5 to thO 1 0 3 7-0 to 8-5 4 0 iJ 6 "J ..,.

,.6-5 to a-o 4 0 II 6 ,., d-

6·0 to 7.5 6 0 " 8 J

5-5 to 7-0 5 1 '" l' '):

s-O'to 6-5 11 2 17 Ji

4:.5 to 6-0 10 4 17 ,:;

"-0 to 5-5 9 3 ,'" 23 I I

3-5,to 5.0 .7 2 :t 22 1/ ..-3.0 to 4-5 5 0 20 d

2-5 to 4-0 2 2 ;-. 23 . '.~

2.0 to 3-5 3 2 23 }'1·

1-5 to 3-0 2 4 :!'-, 22 I b 1-0 to 2-5 3 2 " 23 ; ! ,,'

0-5 to 2-0 4 5 q

22 i 1 :;.

0 to 1-5 6 7 .. ' 22 "

-0-5 to ,,1·0 5 8 ..... 1 26 " "

-1-0 to -0-5 4 4 22 -1-5 to -0-0 2 8 :)

., 19 .)

-2-0 to -0-5 0 7 1a -2-5 to -1-0 0 6 .' 17 1/ ,)

TABLE 1Zt

- 113 -

APPENDIX_ II_

PERCENTAGE EXPOSURE TO THE AIR AT DIFFERENT SHORE LEVELS A.T TAYLOR'S MISTAKE.

Ft above. 26 MaI- 15 Sept.- 2 Jan.- 16 March- Total Percent-or below 9 June r 29 Sept. Ie" 30 Marcn_ (Max_ .!S! C.D. ' ... r!44) EXpOsure_

8-5 336 336 336 336 1344 100-0 8-0 336 336 335 334 1341 99-8

·7-5 336 334 330 324 1324 98-6 7-0 336 329 316 308 1289 96-6 6-5 334 321 303 ·280 1238 92-1 6-0 314 309 282 258 1163 86-5 5-5 273 279 247 241 1040 77-4 5-0 244 249 228 220 941 70-0 4-5 217 216 200 201 834 62.1 4-0 195 194 180 181 750 55-8 3-5 176 173 164 161 074 50-1 1-0 160 156 146 144 606 45-1 2-5 143 140 130 125 538 40-0 2-0 123 118 111 109 461 34-3 1-5 96 97 . 86 83 362 26-9 1-0 64 62 55 49 230 17-1

-5 31 23 28 25 107 7-9 0 19 0 8 8 35 2-6

- -5 9 0 7 2 13 1-0 --1 2 0 2 0 2 0-1 --15 0 0 0 0 0 0

- 114 -APPENDIX. III.

LIST OF PLANTS AND ANIMALS FROM TAYLOR'S MISTAKE.

ALGAE.

CHLOROPHYCEAE. Bryopsls plumosa C.Ag. Bryopsls vestlta J.Ag. Bnopsls sp. Codlum adh~rens C.Ag. C odium fragll e Cladophora sp. _ Cbaetomorpha darwlnll Kuetz Chaetomorpha area Enteromorpha minima Kuetz Ulva lactuca rlg1da C.A.g. Ulva ap.

PHAEOPHYCEAE. Eetoearpus conlfervoldes Roth Eetocarpus ap. Halopterla hordacea Harv. Dlctyota d1chotoma Huds. Zonarla subartlcularta Lmx. Ratala sp. Leatheala d1fformis L. Myrlogolla llndauerll Kylln. Papenfusslella lutea Kylln. Splaebnidlum rugosum L. Desmarestla flrma Ag. Ilea fascla Muell. Seytoslphon lome~tarla Lyngb. Colpomenla slnuosa Roth. Adenocystls utrlcularls Bory. Seytot~us australls H.et H. Macrocystls pyrltera L. Blossevlllla sealarla J.Ag. Carpophyllum maschalocarpum Turn. Hormoslra banksll Turn. Sareophycua potatorum Lablll.

RHODOPHYCEAE. Caulacanthus aplnellls Kuetz. Gelldlum caulacanthum J.Ag. Laurencla ap. Polyslphonia sp. Polyslphonia sp. Polyslphonia sp. Bostrlchia arbuscula H.et H. Heteroslphonia conclnna Fkbg. Call1thamnion sp. Call1thamnlon sp.

PROTOZOA , Cll±a:e!:

- 115 -Eupt1lota formoss1ssima Mont. Melobesia ap. Lithothamn1on sp. Corallina officinalis L. C orallina ap. Corallina ap.

ANIMALS.

Tr1chod.ina ap.

COELENTERATA Hydrozoa

Hemid1na intermed1a Hilgendorf Sertular1a bispinosa Gray Sertulal"ella crassicula Sertularella simplex Lendenfe14 Obelia nodosa Obeli,a caughteryi Bale Plumularia setacea Ellis Orthopyx1s delicata Trebilcock Syncoryne tenella

Act1nar1a Metr1d1um phanopteron Parry Sagart1a albocincta Hutton Actinia tenebrosa Farquhar Anemonia ol1vacea Hutton Anthopleura aureoradiata Stucky Anthopleura 1nconsp1cua Hutton Anthopleura minima Hutton Cradactia~agna stucky Cradactls pl1catua Hutton Thoe d1 aphanes Parry

Alcyonar1a

PLATYHELMINTHES TUrbellar1a

Leptoplana brunnea Cheeseman?

NEMERTINEA Several spec1es 1ncluding

1. P1nk nemert1ne perhaps Amphiphorus heteropthalma Scbmarda.

2. Black nemert1ne.

GEPHYREA Slpunculo1dea

Phy~oaoma annulatum i-l'-'.ii·o",,\.

- 116 -

POLYCHAETA Err antI a

EUphione11a polycbroma Scl::unarda Eualiaa microphy11a Scbmarda Bualla ap. Steggoa brevlcornls Ehlers Phy11odoce castanea Marenz Podarke augustlrrons Grube Nerels australls Scbmarda Nerels val1ata Grube Berels rU£lceps Ehlers Berels maD~lca Benham Nerels neozealanicus Benham Sy111s c1osterobranchiata Scbmarda Sy111s ap. Sy111s sp. Sy111s sp. 8'1111s sp. Pln1 osy111 s sp. Exogone heterochaeta Mcl. Auto1ytus monoceros Ehlers Grubea ap. Marphyaa sp. Lumbrlconerels sphaerocephala Scbmarda Lumbrlconerels ap. Stauronerels sp. G1ycera ovlgera Scbmarda

Sedentarla Polydora monalarls Ehlers Sco101epls ap. Clrratulua nucballs Ehlers Heteroclrrus sp. Adouin1a ap. Sabellarla splnulosa Chone ap. ADlphi trl te .sp. Sabella ap. Pomatoceros coeruleua Scbmarda Pomatoceroa ap. Galeolarla hystrlx Morch Splrorbls zealanicua Gray Serpula sp.

CRUSTACEA OIrrlpedia

Chimaealpho columna Spengler Chamaeslpho brunnea Moore Elminius pllcatus Gray Elmin1ua modestua Darwin Tetracllta purpuraacena Wood PolLic1pea splnuosua Q. & G.

Isopoda

- 117 -

Scutuloida maculata Chilton Idotea elongata Miers Dynamenella huttoni Thompson Isooladus armatus Milne-Edwards

Amphipoda Hyale rubra Podoceros cristatus Thompson Caprella aequilibra Say Pariambus typicus

DecapOda Cancer novae-zealandia Jacquinot & Lucas Hem1grap~ sexdentatus Milne-Edwards Oval1pes bipustulatus Milne-Edwards Cyclograpsls lavauxi Milne-Edwards Paramitbrax latrelli Miers

ARACHNIDA

Pinnotheres pism L. Eupagurus novae-zealandia Dana Petrolisthes elongatus Milne-Edwards Leander affinis Milne-Edwards

Desis mariana Hector

PY'CNOGONIDA

MOLLUSCA LOrlcata

Ammothea dohrni Thompson

Eudoxochiton nobilis Gray Cryptochoncus porosus Burrow Aoanthochiton zealanicus Q. & G. Ilaorichiton caelatus Reeve Maorichiton metonomazU8 Iredale Diaphoroplax biramosa Q. & G. Gu1ldingya obtecta Pilsbury Frembleya egregia H. Ada:ms Amauroohiton glaucus Gray Sypbarochiton pelliserpentis Gray Sypharochiton sinclairi Gray Ornitochiton neglectus Rochebrune

GastrIJpodi - aliotiS iris Martyn

Melagraphia (Monodonta) aethiops Gmelin LunelIa (Turbo) smaragda Martyn Cookia (Astrea) suloate Martyn Patelloida corticata corallina Oliver N'n1':nA~mAA nA1"vi Aonoidea Oliver ,...

- IlS -

Cellana (HelciDnis~s) radians Gmelin Cellana (Helcioni80~) ornata Dillywn Cellana ornata inconspicuous Gr~ Kelaraphe oliveri 7inIay Melaraphe cincta Q. & G. Rhizellopsis varia Hutton Sisapatella (Calyptrea) novaezeelandae Lesson Buocinulum lineum Martyn !.elsia (Thais) haustrum Hutton Lepsiella (Thais) scobina Q. & G. Lepsiella scobina albamarginata Deshayes Lepsiella soobina rutilia Suter Neothais soalaris Menke Xymeme plebejus Hutton Arohidoris wellingtonensls Abraham Glossodoris aureomarginata Cheeseman Doto sp. Siphonaria zealanica Q. & G. Siphonaria australis Q. & G. Benhamina obliquata Sowerby Gadinia nivea Hutton Onchidella nigricans Q. & G.

Pelecypoda

BRYOZOA

Mytilus canaliculus Martyn Mytilus planulatus Lamark Aulacamya (MYtilus) magellanicus maoriana Iredale Volsella (Modiolus) neozealanicus Iredale Modiolus impacta Hermannsen Ostrea reniformis Sowerby Amphidesma subtriangulatumWood Paphrus (Paphia) largillierti Phillips Protot~aca (Paphia) orassioosta Deshayes

Several unidentified species.

ECHINODERMATA Asteroidea

Asterina regularis Verrill Calvasterias suteri Loriol Astrostole scabra Hutton Coscinasterias calamaria Gray Allostichaster polyplax Muller & Trischel Asterodon miliaris Gray

Echinoidea

TUNICATA Eveohinus ohloroticus Val.

Aplidium thomsoni Brewin Didemnum QIUldium Savigny

PISCliS

- 119 -

Polycitor 8p. Distaplia taylori Brewin Corella eumyota Traustedt Botryllis lea chi Savigny Asterocarpa cera Sluiter Chemidooarpa bicornuta Sluiter Pyura subuoulata Sluiter Pyura cancellata Brewin Pyura pulla Sluiter Pyura pachydermatina Herdman

Tripterygion medium Gunther Tropterygion varium Forster Aoanthoolinus quadridactylus Forster Diplocrepis punioeus Richardson Pseudolabris oelidotus Forster Clupea antipoda Hector Agnosttomus torsteri Bl. Coridodax pullus F'ors.t-e(' Latella baoohus . Fo~~ter

- 120 -

ACKNONLEDGEMENTS .

I wish to record my indebtedness to Professor

Percival for his helpful advice and criticism; to

Professor Chapman. Auckland University College. for

assistance with the identification of Algae; to Miss B.

Brewin. Otago University, for assistance in identifying

the Tunicatesj to Sir William Benham for the loan of

valuable literature; and to the Canterbury Museum. for

the loan of collections.

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